If your real DIY type of guy then you can build one with components off of e-bay and the internet. I built mine using the Arduino
processor, 12VDC gearmotor off internet and a relay board to control motor forward and reverse. some misc fuse holders, 4
limit switches and wiring.
Total cost was around $125 including plywood for control box and door. I used an inexpensive photocell and relay board
bought off the internet to open door at dawn and close at dusk, it is adjustable and was under $10...two limit switches to
control stopping door when opening and closing. Added two more limit switches to turn on small lights
I can see from my computer room to confirm door actually opened and closed. It all runs off an old car battery I had laying
around and I keep a small charger on it.
So far it has worked flawlessly but did spend many hrs getting everything to work like I wanted it to but then I am retired and it
was a challenge for me. I am not interested in building and selling them but would be glad to supply some photos if
your interested.