The base lines are all pretty similar, but if you're ordering, first look to see how far the chicks will be shipped. The closer, the better, as it's less stress and creates a better chance for survival. Price can be variable, but it's better to pay a little more for a closer ship, than to pay less and have them shipped cross country over three days.
After that, it's all about care and raising, as you might have already realized. Unlimited clean water, good feed, and try to keep up on the poo in some way or another. Keeping the stress down for them helps - steady temperatures, not being chased, not being overheated, not being picked on etc. They aren't a rocket science, but they seem to do well on a steady, reliable schedule of care.
Some of the popular places are Welp, Central Hatchery and Schlecht, among others. I prefer Schlecht, but they ship overnight to my area, so it's nice.
