Complex sentence: Some bike co-ops charge users an hourly fee between US $5 and US $15 for the use of their space, tools, and assistance; they usually waive the fee for low-income users.
Split into simpler sentences: Some bike co-ops charge a fee--between US $5 and US $15 per hour--for the use of their space, tools, and assistance. They usually waive the fee for low-income users.