5 minutes with a search engine tells me somewhere in the range of $300US including preamp, receiver and case, software, materials for antenna, and coax. Doesn't include shipping or your time.
I must say this is a pretty interesting/cool idea. I didn't see anywhere that indicated how high you have the antenna mounted. Do you need a horizon to horizon view?
Horizon to horizon is nice, but not necessary, as you'll get pretty much all the image you need.
My antenna is about 4 feet off the roof.

No pre-amp here, and my elevation is only about 60 feet.
Must get up there again and replace the tape with some zip ties for the coax.