This is a pretty neat tutorial, thanks for sharing with us! I need to make some adjustments to my patterns as well (petite alterations) but I use large pieces of tracing paper. The plastic trash bag will probably withstand more handling over time though.
I can't help with an answer to your question, but I wanted to let you know about another sewing community online, PatternReview.com. They have great people w/ much knowledge on sewing and a very active section for sewing machines, and sergers. If you don't receive a response here, you should post your question on their serger forum. I hope you can find a machine that will suit your needs!
I don't know what your definition of "affordable" is, but you can check out Wild Ginger software. Their professional pattern drafting software, Cameo, has a grading module that you can buy to add to their base pattern drafting CAD system.
I have never actually used the grading module but the pattern drafting software is what we used in my computer pattern making course. There is a learning curve, but once you get it drafting by hand just seems soooo slow. I have the base software and 4 other modules for womenswear and menswear. I really enjoyed using it in class and on my own once I learned the quirks of the program.
Have you thought about getting some books on grading patterns?
Let me know if you have questions on the software, if you have specific questions on the grading module you will need to search the WG forums. Hope this information helps.
In general, used items are just that- they have had a previous owner and a previous life, and nothing is really guaranteed about their current state. Refurbished usually means that there was something wrong with the machine, it was returned to the factory (or a private party) and was returned to its original condition.
Often times private parties who fix up machines label their items as refurbished and list them that way on Ebay, especially vintage sewing machines. However, some people take advantage of the term and use it very loosely- even into the false advertising realm. You really need to do your research on the seller and what they mean when they claim.
I have no problem buying refurbished items overall because they are generally cheaper than a brand new one, and often times in better "looked over" condition because someone had to put more time to diagnose its original issue and restore/fix it.
This store you ask of, do they have references they can provide so you can contact other refurbished sewing machine owners to ask about their experience? do they offer any warranties on their machines? It all comes down to you doing your research on the machine that will fit your needs, and getting the chance to go to the store to test out some potential models.
I personally have no qualms about getting a used or a refurbished machine- as long as I feel I have done the research to my best knowledge/ability at the time. Remember, sometimes a lemon is just a lemon no matter what. Just work hard on getting to know what you are looking for and try to get the best deal on it. Have fun shopping!
Another possible model would be the Kenmore 18221 from Sears. Prices for these machines are <$200 USD.
One thing of note though, the TB-12 does not have adjustable presser feet pressure, something many people recommend if you are sewing with different varieties of fabric. You may want to research on that topic on your own. I am not sure if the Kenmore has this feature.
I do speak French but it's been a while so I'm going to stick to English.... I don't know the answer to your question about the Swedish tracing paper, but do you have access to regular tissue paper? Wax paper from the kitchen can also work for tracing patterns.
I would recommend you checking out PatternReview.com. There are a lot of sewers from Europe on there, and I am sure they can help you w/ advice regarding shops in your part of the world. There is also a search function where you can look up reviews on stores in your country (as long as there are reviews that is). I assume you live in France, I know there are a few fabric store reviews on Parisian fabric stores- maybe some of them have websites?
Hope this can jump start your search! (BTW, not to take people from Craftster, but PatternReview is geared specifically towards the sewing community and there are many experienced people on there who are very gracious with their sewing knowledge )
For different varieties of fabric, you will want a sewing machine w/ adjustable presser foot pressure. You want to be able to set these settings yourself to accommodate the various fabric types you want to sew.
In regards to models and brands, this is something you'll want to test out as much as possible at a dealer. I just ordered a machine from the US (I live in S. Korea) and I am trying to bond w/ it but I don't know if we're clicking so it might be returned. If you have access to a variety of machines to try them out, I would do it.
I also am realizing I am more partial to mechanical and/or vintage machines that are well built. I prefer thinking for myself at the machine vs. pushing buttons and letting the computer do all the work. I am also strictly a garment sewer and my needs for that don't require fancy stitches. You will want to think about what kind of sewing you're planning to do on your new machine.
Using the correct needle for your machine is also very important. Be sure you read up on that topic.
Take your time finding a machine, it's something you will probably want for a very long time and it could be a long process. Sometimes even with lots of research you still might not bond with it (like me and my Janome Threadbanger!). Good luck in your hunt.
You can definitely sew garments w/ out the need of a serger. In fact, high end and couture level garments aren't serged at all and instead finish the edges using bound seams such as bias bound, hong kong finish, or french and flat fell seams. These techniques will take longer to apply than running your seams through a serger, but if done well, they make your garment look polished and professional. Ofcourse, there are great looking items that are made that use overlock (serger) machines. They make life especially easier w/ knit fabrics, and can look just like RTW on the inside because that's what many clothing manufacturers use in their factories.
I would make a point to learn how to do the different seam techniques before you spend money on a serger. That way, you can continue to make clothes the traditional way and then learn the "shortcuts" via serging.