I'm no light expert by any means but I can give you what I know from the year of experience of filming weddings I have (not a lot, I know).
Decide what you're lighting and maybe get different lights for every situation. If you need to light a room or dance floor, you might need a strong 50w or 100w light. This'll go beyond your budget, it'll be $150+ probably. If you need to light closer subjects, you might do with a 10w light.
I bought a 150w light on Amazon.com for $40. I got what I paid for. Within minutes of turning it on, I could smell something burning and smoke was coming out of the light.
Right now I use a Canon VL-10 10w light on both my cameras I use for filming weddings. They cost around $80; check out Amazon. 10w may not seem like much but the punch this light puts out really impressed me, and I'm very happy with it. The best thing about it is that it uses the same batteries as my Canon camcorders