In an effort to get this thread back on track, I would like to reveal to you the dirty secret about garage sales: they are actually priced randomly!
I've heard a lot of interesting speculation about garage sales, all of which are false.
First of all, a garage sale item is almost never priced for profit or even with the cost to REI in mind. Items are marked down according to what the employees think is a fair price for them. If you see a dirty, grimy Marmot Precip on the rack for $30, it's not because that's the cost of the item to REI, it's because the employees at the store don't value Marmot Precips very highly and they wouldn't want to pay more than $30 for it.
Garage sales are two things: a membership benefit or driver, and also simply a way for each individual REI store to attempt to recoup some of the money lost in negative sales transactions (returns). Negative sales come out of a store's stats and garage sales can help bring those up.
If an item is marked down a second time during a garage sale, it's not because it's the lowest price REI will accept, it's because the warehouse is overflowing and the employee managing the sale really wants it gone.
Finally, garage sale items are not charged against vendors. Only items that are clearly due to manufacturer defect are sent back to vendor.