Bettas and Snails

Question
QUESTION: I have an approx. 3.5 liter bolw for my betta and i was wondering if i could get a aqua snail to live with him.
if so, which type?
would i need to feed the snail?
how much would he cost?
where could i buy him?

ANSWER: I must ask a few questions first to determine if the fish needs a different tank:
is there a heater for the betta (betta's are tropical fish and require atleast 83F)?
is there a continuous supply of air for the fish?
is there a filter for the fish?

If all the answers are yes then go ahead with a snail. You should get a snail that eats algae so you don't have to worry about feeding it. Snails don't usually cost much. Try to go with a lighter colored snail (darker ones die easier)and handle it with care (or it WILL die)

---------- FOLLOW-UP ----------

QUESTION: He doesn't have a personal heater, (but there is one in his room)
I heard that Bettas go to the surface for air, as does mine, thus i haven't installed a bubbler.
there is no filter, but his tank is cleaned very well once a week.

Answer
I would get him a heater. The snail would like the bubbler (they don't breathe surface air) and if you do get more fish they would like the bubbler too and when I put a bubbler in for my betta, he became way more active.
I would get a filter and that way you only have to clean the tank once a month.