[JustOneMore20]

Check Home Depot and/or Lowe's. They may sell 2ft shop lights. Those will hold 15 watt bulbs though, so 2 of them will only give you 30 watts. You probably won't be able to put more than 2 over the tank, since it will be crowded. If you can find double shop lights, 2 of those might fit and that would be 60 watts. I have no idea how much they cost though.

If its a stock hood, then you can only use that size bulb (probably 15w) and if its a full hood, you won't have room to put anything else over the tank, meaning you'll need a new fixture.

Is the lights that came with it fluorescent lights? How many bulbs?

The need for co2 increases with an increase in light. You don't have to inject co2 until you have about 2.5 watts per gallon (roughly) over the tank, which in your case, would be about 50 watts or so. Even then, if you have enough fast growing plants, you may not need to inject co2.

DIY CO2 does work on tanks about 30g and below.