The right light

You could do an open tank with 2 hanging lamps over the tank. You can swap out the incandescent bulbs for screw-in spiral CF bulbs in daylight (6,500K). 2 of the 15 watt CF bulbs would give you 30 watts over the tank, which would qualify as a very low-light tank. Plant choices would include anubias, cryptocoryne, java ferns, java moss. Sorry, but I'm not familiar with the lighting needs of a banana plant, so I can't comment on this. You could also suspend a fluorescent light fixture over the tank if you wanted. The problem with open tanks is:
1) Fish jump out
2) Evaporation of tank water
3) Water cools quickly, heater stays on

Another option is to get a glass top for the tank and place an aquarium light fixture (or even a shop light) on the glass top. You can get fixtures with single or dual bulbs, depending on how much light you want over the tank.
25-45 watts of light over your 25 gallon tank = low light plants
50-70 watts = medium light plants
Anything above this will probably require addition of C02.

A third choice is to get a hood with fluorescent lighting built-in. As I mentioned before, you'll need at least 30 watts of light if you want to grow most of the low-light plants.