I didnt want to spend a lot of money on wood so I looked in the paper and found an old wooden closet for 20 bucks. The back boards were thin so I bought a piece of scrap wood for 10 bucks and attached that with metal corners. I water proofed it all with a water based polyurathane. I used the original doors but went to the hardware shop and had them cut 3 inches off each side of each door making a frame. In the frame I inserted plexi glass and fixed it with silicone. I do have the problem now that the doors are a bit short, but I think I'll just drill new holes for the hooks. On the inside of the cage I made a rock wall with styrafoam and painted it grey. There are also some areas with cork. It's still not done though.
So, if you want a moderately cheap cage where you dont have to do much carpentry work, just buy an old wooden closed.
ps, after the polyurathane was dry, I put aquarium safe silicone in all the cracks along the parts where the boards tough. That made it water proof.