Bettas can live for a few years if they are properly cared for. I had one for at least three or four years awhile back

Plastic plants are OK as well as a 2.5 gallon bowl should be fine. Grant it, the more space the betta has, the more active it will be. But its not too small.

Just keep in mind that they need a space at the top of the tank because bettas are surface breathers. So just in general if you wanted to put your betta in a bowl with a real plant etc just make sure there is enough exposed surface area for them to come up and breathe. ♥

I recommend getting your betta from a fish specialty store, NOT from a store like WalMart. Stores like WalMart DO NOT specialize in animal care so many of the fish they get are sick or aren't properly cared for. Also when you purchase fish from animal speciality or fish stores most will come with a guarantee so if the fish dies within the first X days from the purchase date you can usually bring it back for a refund or exchange.

Good luck!