I will let you in on a little secret - find a tournament director of a sanction that provides game balls (like ASA qualifiers), and ask them if you can buy their used game balls after the tournament. We have bought buckets of them for $1 each.....
If that is not an option I would recommend the TRUMP balls. You can find them reasonably priced online and they last longer than most.
What are people using. The ones I have are now egg shaped. Looking for a good practice ball that will last.