If your 29 gallon tank is like mine, it is about 30 inches long, and that is an odd size to find lights for. The best I was able to do, cheaply, was 24 inch fluorescents, which are 20 watt in T12 or 17 watts in T8. I was able to grow plants reasonably well using three of the T8 bulbs. You could watch ebay regularly for good prices on a 30 inch hood. And, there is always a chance that if you post a shop n swap listing for "want to buy" a 30 inch hood, you might get one for a good price.
Another option is to look for spiral compact fluorescent lights, for example, ones with round reflectors, and get three of those to suspend over the tank. I have read here that WalMart has them.
Somehow, you do need to find a way to get up to 50 watts or so of light on that tank.