Another vote for the Tack Exchange.
full disclosure: I have stuff consigned at Middleburg Tack Exchange. But, based on my experience there, I’d definitely make that a priority stop and allow some browsing time. There was a large inventory of stuff when I was there, but nicely arranged and not randomly tossed and hung hither and yon for customers to dig through (like some other places that take consignments). Prices seemed pretty good.
Moreover, they combed through my offerings and took the perfect and near-perfect of them, rejecting anything that looked used. So I bet if you do find something you decide you “need”, it is likely to be in excellent condition at a nice price.
For lunch, Hunter’s Head Tavern in Upperville mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm