Axolotls usually stay into their larval form all their life , hence they are fully aquatic. However very seldom there are some that will metamorphosis to their terrestrial form but from what I have read they do not live very long once they get there.
More you can read here
http://www.axolotl.org/index.htm about that and about sexual maturity here
http://www.axolotl.org/biology.htm.
I personally would not even consider breeding them unless they have at least year and half or two on them.
If you have true axolotl
ambystoma mexicanum then it should remain aquatic for its whole life.
You live in USA, petco or other chain stores often have dollar per gallon sale , you can get 29G for 29$, or just Craigslist some tanks often some there for free pickup.