I've recently ascertained the black art of homemade
decals and it can work really well with the right decal kit and a good inkjet photo printer - and a lot of time for learning how to make good computer graphics and how to scale correctly.
The printed
decals HAVE to be clear coated right away as soon as they've dried, and you have to cut them out precisely since you're printing on one A4 size decal, but it looks really good when you've got the hang of it - if you're prepared to put in the hours... (and the money...)
The benefit is that you can have any decal you want but the downside is that it costs a bit to get started and to learn how to use them...
My photo printer is sadly in need of replacing so I'm going to wait for now but there are really good instructional videos on youtube on the matter.
If not then eBay is your friend for finding available
decals - if they exist.