I bought a Lange power hoist. I'd suggest going to Harbor Freight to buy the motor, and just make one for yourself.
I'm satisfied with mine, although I've mounted it twice now. The first time, I mounted it directly on the ceiling. I have a 9' ceiling and with the motor on the ceiling it just had the top hanging too low. I moved the motor to the wall and put 2 eye bolts in the ceiling and gained about 4-5 inches of clearance. I also have 4 other eye bolts in the ceiling above each corner, that I have 2 ratchet straps criss-crossed to keep my top stable while its hanging.
As you can tell, it's quite an ordeal.... but then again I appreciate the ease of use, as I can raise & lower with one hand on the switch and one hand guiding the top.
Sometimes I think the Harken might be better, but I didn't like the idea of the ropes coming down my wall, and the slight chance someone accidently unhooks it and the top drops...
Single handed operation was the deciding factor for me.