Replacement Convertible Top

My first post. I have a 99 M3 convertible which is barely broken in with 71,000 miles. Baby needs a new top. Molding (Edging) is pulling away around rear window and tension straps need replacing.

GAHH wants $886 for the top and tension straps. Topsonline.com wants $539.00 ($347.00 cheaper than GAHH). I live near Tampa, FL and have talked to 5 different installers.

Appears the going labor rate to install top is $500.00

Some questions for anyone with experience in getting a new top:

1. Is GAHH really worth the additional money? Is there that much difference in material?

2. Does it really take 6 to 8 hours to replace the top or is $500 just the going rate because it's a BMW?

3. Last...my wife and I are thinking about trying to do the install ourselves. Stupid idea or what?

Thanks in advance to anyone who responds.