Thanks for reaching out!
How each store approaches the turnover of a rental fleet, whether bikes or snowshoes, can vary depending on location. Your best bet is to reach out to your local REI store and ask if there are any details regarding the former rental bikes coming up for sale. Typically, if rental items are sold, we do not take reservations or have a 'list' for buying items; purchases are first come, first served.
Hopefully this helps, thanks!