R-134a Refrigerant 12oz can for $3.35 ($2.98 after rebate) at Menards B&M only.

https://www.menards.com/main/tool…985870.htm
This is about the cheapest that I’ve ever seen for these cans. You have to go to the store to avoid the possibly upsetting shipping and processing fees, so I’m marking this as B&M only. The mail-in-rebate comes in the form of an in-store merchandise credit. Forms available at the customer service counter.