Can anybody recommend a good quality insulated garage door that will work with the Liftmaster 8500 opener? Did you go through Home Depot / Lowes? Elsewhere?
Did you self install or hire someone to install it?
I'm not familiar with the Liftmaster 8500 but I recently obtained pricing on some 18x7 insulated doors from a local garage door company. I know it's bigger than what you want/need but I just thought that I would share for comparative purposes. A garage door is not something I want to mess with installing, adjusting, etc so the prices below are all installed, using my existing opener.
18x7 Raynor AP138, 1 3/8" thick, R13 for $1365
18x7 Raynor AP200, 2" thick, R18 for $1620
CHI 2283, 2" thick, R10 for $1330