If you get this new tank or any other tanks, you should try to breed fish to make some money. You won't make thousands but will make enough to pay for the hobby and allow you to buy more tanks and equipment.
Pearl gouramis aren't big sellers but if you have a few shops nearby or know a fish wholesaler, you can get rid of lots of young fish to them.
You could get a group (1 male & 4 females) of peacock cichlids and breed them in the tank. Sell any babies.
Some of the rainbowfish sell and if you can get good stock you can sell a lot of them. Melanotaenia praecox is a good one to keep and breed. They are brightly coloured, don't get too big and produce a lot of eggs and subsequently young. You can sell the young fish at 2-3 months of age.
Mouth brooding bettas are another option.