Live plants are going to be difficult in a 75 with stock lighting. Many of the plants at the chain stores aren't even aquatic anyway. If you're looking to get into live plants, I'd suggest ordering online if a chain store is your only local option. A lot of people use shop lights from Lowe's/HD to bump up the light intensity without spending a ton, or you could upgrade to power compacts or
HO T5s if it's in the budget. There are quite a few websites that would save you a ton of money over buying locally.