So, there it is. It works, but should you build one? Well that depends on what you want to get out of building/buying a 3D printer. If you just want to print 3D things for cheap then no, I wouldn't build one. Get a Makerbot or an Ultimaker or build a RepRap. If you want to tinker and possibly get some amazing prints and don't mind that they cost a bit more to print than the others then go for it. I would love to have some other people testing and thinking up new ways to tweak this.
As for cost of building the machine, I think I spent about $600 - $800 for everything. Less than the extruder printers but the material cost is about 4-5 times more so it's not really the economy option.
There are also other ways to print with UV cured resins, like using a DLP projector to show images for long enough to cure a layer. There is one person that has made one that seems to work well but it looks like it is closed source and going to be expensive when he starts selling it. There is also a Yahoo group called diy_3d_printing_and_fabrication
with people sharing their DLP based builds and resin tests.
You should have used a laser galvanometer (galvo)! Sounds great, if you find one accurate enough for under a few hundred dollars let me know!
Just for fun, the picture above shows most of the bad prints I've made so far.
I probably missed something so let me know if you have questions and I will get to them as soon as I can. Thanks for reading.