I had the same problem with my 20G. I'm not sure of anywhere you can buy the frames for an aquarium. Regardless if you could find them or not, you'd have to find a way to get the wood ones off without damaging the glass...those frames hold you tank together pretty much...I would not mess around with trying to remove them, personally.
What I did with mine: I took the tank out back and used some sand-paper and very gently sanded the wooden frames, I then hosed down the tank and cleaned it out really well and let it dry overnight. I then used some painters tape(the blue stuff) and painted the frame with a foam brush. I wouldn't reccomend using spray paint because the over-spray would go into the inside of the tank, toxic paint can't be good for fish. I put about 3 coats of paint on and it hasnt chipped or rubbed off or anything in 6 years. I used regular satin black paint from Lowes.
Hope this helps....maybe you could post some before and after pics!!!