Why? Almost none of it (that I've found - but honestly, by now I have a pretty freaking huge sample size - where there's one A&B item, there's almost always several) has actual full canvassing and some of the "claimed premium" fabrics just don't feel all that good. If you're just starting out maybe it would be good, but if you're just starting out you need to learn restraint and patience for something really worth your while, not half-measures.
I was tempted by a 100% cashmere jacket once but held firm.
The shirts - eh. Most feature plastic buttons and questionable stitching from what I've seen. I HAVE seen a few that must be nicer make, with MOP buttons and some construction features that were lacking on others (like side gussets) but even at thrift prices, eh - I'd rather be patient for guys to find a Borrelli or something in my size. Again, half-measures.
The ties - honestly, their seven folds are nice. I've only seen them at consignment for $25 and that's more than I'm willing to pay for one. If I saw one at a thrift I'd probably pick it up. The three folds are pretty much junk IMO.
As for Ebay - I've researched it repeatedly and never seen any reliable sales. Sure, occasionally a shirt sells for $15 or so, or a jacket for a few bucks - but for every single one of those there's gobs and gobs that don't move.