Denver’s soaring real-estate prices haven’t just affected renters and home buyers. For musicians and artists, affordable spaces to hone their craft are quickly disappearing. Enter RocketSpace, rehearsal venues on upper Larimer Street and South Broadway that rent by the hour. Temperature-controlled rooms for rent start as low as $8 an hour, and a standard full-band practice room — starting at $15 an hour and costing less each additional hour — comes equipped with a high-quality drum kit, a PA system, two guitar amps, a bass amp, a mixing board and microphones. Most rock bands just need to bring guitars and themselves — no cumbersome lugging of gear. And RocketSpace is open 24 hours a day, seven days a week, so it offers the flexibility that many musicians with day jobs need to make their creative lives work.