As wonderful as older or "vintage" machines may work right now, If you ever have a part break, you may have a lot of problems getting parts. I work for a sewing machine dealer and after 25 years the brand discontinues most of the parts, if they don't work on the newer machines. So you may be able to find replacement parts, but it's going to cost you more and most dealers charge you more to service the machines because they are harder to get into and a lot harder to clean than a new machine.
The computerized machines actually have less moving parts so they are easier to fix than most manual machines so they will give you less trouble and cost you less in repairs in the long run.
As far as singers go, they are very cheaply made which is why they are so inexpensive, and i would definitely recommend that you purchase any machine you get from an independent dealer. You are more likely to get a good deal since they do not have preset prices and you can haggle for a good price. And usually you get perks such as free lessons on how to use the machine as well as deals within the store/coupons. Plus you would be supporting local businesses which is always good.
Now i am biased because i do work for an independent dealer but i recommend Pfaff machines. They are European built and German engineered if you get an actual Pfaff model. The Hobby's and Smart line are a different story.
But being a fashion student myself and for about the price range you listed, a good machine would be a 1500 series machine if you can find one(For an awesome mechanical machine). Or as far as computerized machines, i recommend a 2000 series( 2023 would be the best it has more buttonholes and utility stitches).
You can look up the models on www.pfaffusa.com
and check out where your local dealer is.
And even though i shouldn't be saying it. I used to sew on a Bernina, an old metal one, can't remember the model number, But berninas are also great machine and are still mostly European made which is always going to be a better machine than one built in Japan.
I hope you find a good one! The easiest way to get discouraged is to buy a machine with a million problems.