You could easily do this yourself with a nice DPSS 532nm laser/driver combo from eBay. I just bought one from Techwood IIRC that's 80mW for $25 shipped. You could easily find one with the output you desire for less. The 12mm DPSS module should fit easily into the host and using a positive ground outlay it would only take one wire soldered from where the spring contacts the DPSS driver board connected to the contact for the battery, just make sure you put the battery in "-" towards the output of the laser.
Yes I am with these guys, you should really have a go yourself, very easy to do and people here will give you any help you need, save yourself a heap of money and get great satisfaction every time that Grenade "Glows up"