Easiest and cheapest option for waterslide decals is probably this ebay seller, especially if you're only after standard logos or want light logos on dark backgrounds.

Alternatively, if you're comfortable with basic use of Photoshop/GIMP you can print your own waterslide decals using an inkjet or laser printer. Best place to ask is a local hobby shop but basically they should be able to sell you some clear water slide decal paper which you can then print on to. You'll want to seal the print with either Microscale liquid decal film or Testors decal bond. Note that this won't work for white/light colours on a dark background. Lancalot has done this recently with his Tiger Track custom so he should be able to give you a more detailed guide.


Either way, to use a decal, it helps if you're applying them on a smooth glossy surface. Trim it out as close to the art work as you can to minimise visible edges, dip in water for 10-20 seconds, then gently work it loose from the backing and slide it into position with a wet paint brush. Blot excess water and let it dry in position. Microscale Microsol will soften the decal film and help it conform to surface details. Clear coat over the top to protect them from damage. More detail here.