I wrote a piece about DIY decals for the Tome issue 9 back in 2007. My inkjet printer died a few months ago and I never got round to replacing it. I've now bought a colour laser printer which I'm starting to experiment with. It's quite ridiculous, but I found a Samsung colour laser, brand new and complete with toners, on Amazon, for less than £60 (delivered).
My stocks of decal paper are all for inkjets but they get fried in a laser printer. Don't ask how I know this. If you're tempted to try using a laser, make sure you buy laser decal paper.
In theory, the laser should be much better as the ink is sealed onto the decal paper during printing, meaning that there's no need to coat with protective varnish. The decals should therefore be thinner and more durable and in overall terms, probably a lot cheaper to produce.
You can find the Tome stuff at http://tome.gn15.info/09_November_07.pdf