I can't remember if I've done this already, but I think the most expensive thing I've bought was my Bronica ETR kit. On the topic of digital, most of the stuff I have was given to me as gifts for graduation or some event (x-mas, birthday). Analog equipment purchases usually come out of pocket.
Best deal, I guess would have to be my Minolta Flash Meter II. It was $4 at a thrift store. Oh, but my Yashica T4 was free from the owners of that same thrift store.