Your best bet would be to buy a SF-AW210 and an aixiz module with a lm317 regulator and a 9V battery that should be about 45 - 50 bucks. If you want an actual full built laser then save more and get a kit or get 4 9 dollar ebay 405nm lasers they tend to be between 30-50mw but I think you will be disappointed with how dim 50mw of 405 is.