Following on from my turned-out-to-be-horrible idea for plotting with Staedtler Lumocolor Permanent red ink direct to PCB's, I turned back to the standard method, as it's really down to what you get to do it.
Some cheap FR4 double sided photosensitised boards from an Italian eBayer, at a quarter what RS want for similar boards, before they start adding tax or shipping, and an HP Laserjet 5N printer for less than five packs of Press and Peel, and it should be obvious that trying to shortcut the standard produre wasn't really worth it. The Toner Transfer idea is cool, but it is still VERY fiddly, and can't beat the standard method.
So, cheap printer with AWESOME accuracy, cheap photosensitized boards, leaving just the lightbox as the other vital hardware. Those are NOT cheap. Unless you do it like this:
A dead scanner. It contains the innards of of a light I found lying beside a vandalised street sign one morning, refitted with the right 11W UV tubes. That's it. I just bent the baseplate to distribute the light better, and stuck a bit of aluminium foil on it to improve the light flood. It even lights up the little indicator light directly by fluorescence so it's easy to know it's switched on when the lid's closed. Sometime I'll maybe add a small timer module, those turn up as junk at times...