A few spring to mind, but I am a rampant bargain hunter/flipper.
USA Gretsch 6131 Firebird - SoundControl ~2005. Was mislabeled as an Electromatic at £299, they kept this price even when queried if correct. Sold on eBay for £1k.
Ibanez Musician MC900 - £250 PMT ~2006, soon traded for a 96 Stingray (they were around £750 at the time).
Tiesco 1480 (1969) - last year. Facebook market as 'broken' for £25. Needed 15 mins of electrical work to fix, later sold for £250
Dingwall Combustion 5/2 this year for £750 (Facebook), good condition too.
2011 Rickenbacker 4003 from CashConverters for £1100 a couple of months ago. Loved it visually, but no use to me - sold a few days later for just under the going rate.