Party lights/black lights are not sufficient. Here's a throed form another kingsnake forum that discussed this issue.
http://forums.kingsnake.com/view.php?id=1670433,1673617

I heard someone say once that a pet owner can expect to spend about three times for housing what they spent for the reptile. UV lights are expensive, but I can find a good linear 8.0 or 10.0 bulb for under $15 and then I put it in a kitchen fixture that I bought at a home supply supply store. I use household bulbs for heat and buy the domes at a home supply store also. I try to save a few bucks when I can but still provide what the animal needs.

Iguanas will not process vit D from dietary supplements and need a UV source. They need a varied diet with rich greens that are high in calcium and then a proper UV source (bulb or sunlight for an hour a day) to metabolize the Vit D and process the calcium. There's really no way to get around that and have a healthy lizard.

Congrats on your new little pet!