Peter who works with Reprap has had two blog posts come across my screen lately...
First his entirely laser cut rack and pinion cnc axis.
Although having something cut with a laser cutter or cnc'd is still out of my reach (not by much). This does lower the bar for making a repeatable cnc machine significantly..
But there are still cheaper/easier options... And thats what his more recent post shows..
Reciprocating Laser Cutter
There's two innovations here. The use of Optical disk drive carriages makes for a low power and small scale axis. This uses three.
Secondly he's using a low power (for a cutter) laser. It's a 1watt unit. He's reciprocating the laser on the Z axis to move the focal point through the material. Giving just enough heat to melt some plastic and cut a part.
If Peter gets a chance to read this. I'd just like him to know I'm impressed and I have plenty of old cd-roms if he needs more.