Interesting article on a Delta Robot that just ran a successful kickstarter project.  It is not a 3D printer, but parts could be made from it, and it looks like it could be converted to one. For $100 bucks, it might be worthwhile to look into.  My 2 cents, if they release the code/designs, it should be pretty easy to homebrew your own.

http://3dprintingindustry.com/2014/03/03/wondering-delta-robots-work-get-95/?utm_source=rss&utm_medium=rss&utm_campaign=wondering-delta-robots-work-get-95