Just my opinion ... and experience: I did a lot of research on this, yet I claim no expertise or prior knowledge. But I'll dare to say that I found the whole subject complicated and defeating in so many ways.

I have produced some decals. Among other things, they were compromised by inks that degrded in UV, media that was not the best, the lack of laser cutting, and copying from originals that were not scanned in the best manner. It takes materials, equipment, software, and some expertise or apprenticing in graphics to assure the better result. There are people who have recorded successes — people who were not graphics professionals — Randyjawa being one.

All that being said, my favorite ride at the moment is a '78-'81 4-Star Simplon. I produced a non-period head-badge for this very rare machine using a screenshot of a web jpeg, a very simple graphics app., and an inkjet printer with ordinary non-archival inks. It has altered colors due to UV. But when local bike enthusiasts are trying to ID the marque, it does the job admirably. Besides, it looks genuine in an antique way.

The rest of my work failed more horribly, but I had a bit of fun — that's all.

My conclusion: $40 (your quote) for a professionally produced decal-set on spiffy media is cheaper as well as well-worth the price. If you wanna build 200 bicycles, you should contract to have your own decals produced by a professional graphics house. Or alternately, if graphics is something that really turns you on, invest in it and study yer arse off. There is not a really cheap and or easy way around this, but you can sometimes get lucky.

YMMV and others may give different opinions.

Good luck — L.