First deal that comes to mind for me is getting Kingdom T-Wrecks at Target for like $15, due to what I can only guess was a glitch at the self-checkout machine.

 

Best deal I ever got.. and this was quite a while ago. Almost the entire first season of BW toys ( no Inferno ) on a ebay auction for $80 shipped. This was like 2005 or so. More recent was a storage unit with a huge collection. Cost me $1,300 but it was a TON of stuff. G1 ( including a Fort Max, Scorponok, TM Scourge, and many many more ), Unicron Trilogy, Animated, Alternators, BW, BM, and more. I completed my G1 collection, almost completed BW, added a bunch of UT stuff that I wanted. Sold off the rest of what I didn't need or want for literally thousands of $$ more than I paid.

Commander Rodimus. OH MY! I had the same issue where it wouldn't stay shut. I tried everything. After listening to this episode, I tried flipping the grey thing down. IT WORKED. Just for kicks and giggles, I flipped it back up to see if it would shut. IT WOULDN'T! I flipped the grey thing back down, and IT WORKED AGAIN!!

 

I once got a MISB Galaxy Force Autovolt for $5.

It was the only Transformer toy that store had.