I'll be needing buy or rent bear spray for a 2 week backpacking trip in AK this Fall.  Since I can't take it back on the plane with me, is it possible to buy from REI in Anchorage and return if unused?  Or is there a cost-effective rental option?  Alaska Outdoor Gear Rental charges $36 for 14-day rental which is a big chunk of the full retail.  TIA!