How much UV lamp power is needed to initiate radical polymerization? I'm looking to purchase a UV lamp for initating some radical polymerizations. Is a hand lamp like the type for examining TLC plates (5-10W, like this) enough power to do this, or do I have to buy something a lot more expensive?

In my case, I'm looking to polymerize a fairly small sample (1mm thick, about 100 mm$^2$ of area, encased in 1mm-thick lab slides) and the chemistry will probably be MMA (initiated with AIBN). I'd like to know for my particular case, but it would be great to know if there's some rules of thumb involved (does it depend on the chemistry? does it depend on the amount? Will different power levels give different final results?)
Sounds interesting! These hand lamps typically have two tubes with emission maxima around $\lambda$ = 254nm and 360 nm, respectively. The latter should be just right to excite AIBN and isn't cut off by Pyrex or comparable glas.

More power is obtained from a high pressure mercury lamp, such as the classical HPK 125W, but these lamps are normally used in cylindrical irradiation vessels with immersion cooling.

If you want a complete system with top- or side irradiation, replacable tubes, metal housing and ventilation have a look at the portfolio of companies like LuzChem.