Culvert pipe what ever distance you want. Some kind of system to bring targets to & from berm (clothes line pulley system) works. A few fans behind shooter to move air downrange. You're looking at $75 - 100K easy for a 1 lane range built to indoor spec, not including permits, opposition from common sense neighbors and getting the county to sign off.

here's a link for your reading entertainment. The prices quoted are on the conservative side, for a multi lane unit. They do give some numbers for single lane. We looked in to a commercial lot indoor range 20 - 25 years ago. At that time it was $1 million ish for a 25 yard, 10 - 15 lane building, land not included.

http://www.shooting-academy.com/medi...ng%20range.pdf