How much does it cost for snowboard rentals in colorado?

It will cost about $20-30 for a one day rental which includes your snowboard and boots. It will be closer to $20 if you rent them in Denver and probably closer to $30 to rent them at the ski resort.

The closer you get to any of the resort towns the more they charge. Rent them in Denver or suburbs if flying into DIA. Sent you a link to Berthoud Pass Ski Area on another question of yours that I answered. If you decide to go there get there early because it looks like they limit the number of skiers there per day to 400. I hear that Berthoud Pass is a great place to ski. I haven't been there myself but I just might try it! Until I read your question I forgot the place existed because they don't advertise like all the other huge corporately run ski resorts here in Colorado. If you don't arrive in time to go to Berthoud well you're still in luck because Winter Park and Mary Jane are just minutes down the other side of the mountain!