new to building walls but going in with a couple other guys to build a pretty good size retaining wall. One of the guys has built several hundred walls and knows how to do it right but i am just curious if our bid was in the right ballpark. Currently there is rift raft rock down this hill that is washing away, we are going to remove and save the rock, cut down a tree thats growing in the way and build a wall thats 70 feet long and averages about 15 feet high, curved at the end and tapering down. we gave a bid of $21,500??