i picked up a mint marshall JTM-45. White back panel, plexi front can't remember the year for 100 quid. Sold it a couple of years later about '93 for 400 quid. Wish I had kept it. worth a fortune now.
I bought a mint E-series squier strat for 100 quid 16 years ago. Awesome guitar, still have it.
PRS signature series from 1989 for 1500 quid.
Swapped a marshall super bass from 1973 for a '67 SG jr (not sure who had the best deal there)
Walked into the bass centre in 1991. Only had 450 quid but fell in love with a status 4000 for £695. I said to Martin in there, I only have 450 quid, he checked what he had paid for the status and sold it to me for £450. I was chuffed to bits