What is a rough estimate to build a 8X8 box blind?

That's a big blind! Is it for a handicapped hunter?

8x8 is nice and roomy

Couple of captains chairs, bunk beds, a stove, and a potty of course!

Is it going to have a foundation?

It's not that bad.. costs depends on materials, metal or wood.. how tall of a platform, etc?

No I take my grandkids and my buddy sometimes takes his son-in-law. Would do wood and paint it...about 2 ft or 3 ft off ground...just high enough to keep critters out.

How tall?

I built an 8x4 blind thisseason and really wish I had made it 6x8 or 8x8. I built mine out of materials I had on hand so cant help with price, but dont let the comments talk you into going smaller, lol.
Figuring cost really depends on what materials you decide on. Plywood and shingles on roof or just roofing tin? OSB of plywood? metal frame or lumber? I fromed mine with 2x4 but a lot of people rip them in half and frame with 2x2 furring strips. I built mine like a house. Once you decide what types of materials you want to use, just figure up what all materials youll need and go to Lowes and price everything.

Really depends on how high you want the ceiling. 4x8 is not much cheaper than a 8x8. An 8x8 will take 3 more sheets of plywood plus some structural wood. You can probably build one for $400 versus about $ 300 for a 4x8.

It can get costly depending how good you build it. I put 3 x3 metal edging on corners. Actually metal frame glass windows. Mine is built out of square tubing which will last a long time but costly with self taping screws.