Regarding shampoo bars and colored hair (mine is partially bleached and purple/plum/gold) I can tell you that they are SUPERIOR to any shampoo made for colored hair on the market, and they are for 2 big reasons:
1) Commercial shampoo all have detergents designed to strip your hair, and that causes color loss as well as damage which causes easy fading. Shampoo bars are gentle and do not strip your hair of the natural oils which protect it. You get clean hair without damage.
2) Commercial shampoos are far more acidic than your hair and scalp appreciate, and high acidity will fade any hair color faster, especially semi-permanent colors because those are usually veg based dyes. Ever give yourself an apple cider vinegar hair rinse with colored hair? It just runs like crazy. Shampoo bars are, by their very makeup, more alkaline which helps your color to stay put.
If it means anything, I colored my hair 4 months ago, and the color is still vibrant and beautiful, and only marginally faded.
I should add though, I only wash my hair once, sometimes twice a week with either a cleansing conditioner (not Wen, but might as well be) or with the occasional shampoo bar, and I gave up normal shampoo a couple years ago. My hair is the absolute healthiest it's ever been in my life, it smells wonderful all throughout, no breakage EVEN with regular bleaching, and my hair doesn't turn into straw haybales after bleaching and coloring. Seriously, after I had been no-poo for about 8 months was the first time I had bleached and dyed it again, and I was floored after washing out the bleach that my hair was soft and shiny. It's a lot tougher than it used to be.
Also, when you start using shampoo bars, you just have to be prepared for a few weeks of very unruly, greasy hair because your hair has to detox from what it's used to, and you have to be prepared and accepting of the difference in feel with the bar. It doesn't lather up like regular shampoo (depending on the recipe, it won't lather at all), and your first inclination is to use more and more and more, and then you'll feel as though your hair didn't really get clean. Add in the first part about the unruly, greasy look of the hair during detox, and this is why a lot of women who attempt to stop using normal shampoo go right back to it.
I can't say enough good things about how good the bars are for colored hair. If you're not making your own, just make sure you pay attention to the ingredients list. I've come across a couple homemade bars that used some really stupid ingredients (we're trying to get away from commercial detergents and soaps here... making a "homemade" shampoo bar using Dial soap as a base is just freaking stupid).
By all means, don't be afraid of soap-making! It just looks intimidating at first, but it's really too much fun and lets you create something personally tailored to your tastes. The hardest part is the initial setup and making sure you have a good space in which to make it. Once you have your supplies in order, it's easy as baking a cake. Then the hardest part is the waiting time for while the soap cures lol. They usually smell so good you just want to cut them up and use them right away!
Hope what I've said here has helped put some of your fears to rest