Looking to buy a laser just for a bit of fun. Not looking to spend much, maybe £30-40 max, but I'd like a good quality, fairly bright laser that runs off lithium batteries. I'm a big fan of the Sanwu Pocket Laser, however it's a bit expensive. Are there any similar products in a lower price range? I'd also be very happy to build one myself, out of parts, if that's a reasonable option. Really any suggestions for good quality budget lasers would be very appreciated.