They're actually REALLY easy to care for! Here's the TL;DR on care: You need about 10 gallons per axolotl, and you can't use gravel as a substrate - barebottom, sand, or slate is totally fine. (The love to eat gravel for some reason, which obviously is really bad for them.) Other than that, you feed them everyday as babies/teenagers and then twice a week as adults, and they eat earthworms! You can also feed them bloodworms, blackworms, crickets, or sinking pellets. They prefer cold water (65 - 70 degrees) and are freshwater critters. :) Lifespan is about 10 - 15 years.

As for cost, they are actually quite affordable! Depending on the color you'd like they go from about $10 - $25, and then you should expect to pay an extra $15ish more for shipping. I'm actually raising some babies right now that should be ready in a few weeks, so if you're really interested and live in the US I could totally sell you one. ^-^ Let me know if you have any other questions! Also this forum is amazing for axolotl information: http://www.caudata.org/forum/