Not sure if this is my most expensive, but it is a Super Graphic kit for about $300

Best deal was a whole darkroom with a Durst 4x5 enlarger, a Durst 6x6 enlarger, tons of Durst stuff, lots of Jobo stuff with a CPP-2, a whole lot of darkroom gear, 12 8x10 and 20 4x5 new in the box film holders; I think the list could go on for a few more lines and the whole lot was free.