Better off buying good genetics methinks. How much THC etc. does one need in a bud? Take an extra puff. Or two.
Chasing the last possible couple percent just ain't worth the time, effort, and expense to me. The weed I grow without it does the job quite nicely already, even in spite of my screwups.
Although to be honest, I did try a few UVA bulbs in my screwin arrays. I have no idea whether it made any difference, but if it did, I didn't notice.
Different strokes folks, and happy growing all, UV or no.