I was actually thinking of something like this: http://www.bareconductive.com/shop/electric-paint-50ml/

It wouldn't be cost effective for a single heated bed, but multiple or for a large bed it may prove cost effective. I have a pretty large bed for my printer and would end up spending about $100 on a PCB heated bed for it: http://m.ebay.com/itm/18-X-18-Heatbe...-/261374879832

A lot becomes cost effective if the standard size heated bed doesn't do it for you.