You need eyes up your backside to buy anything at the Washington as there's PLENTY of shite to sift through there & from what I saw recently people are paying strong money for pisspoor cars - indeed look at yourself - you've got about £3500 in an 11yr old diesel 3 series. You could buy a proper one with a test drive from eBay for less than that! If I had to rely upon purchasing my stock from there I'd soon be in the Jobcentre.
We've all been caught in the past, get rid for whatever peanuts you can get but if you think you're going to wipe your nose at the block with a "P/x direct" or "no name" sticker then you must be sniffing glue.
As you're trading & are new to the game you must be doorstepping - I'd suggest you leave all of the mid range German dross to the pitch lads. The fussy, greedy & overcautious "prestige German car buyers" (all big talk, small pocket merchants imo) aren't what you'll make any money out of on your doorstep.
Just my two penneth worth, I don't mean to sound harsh but this is how I see it.