
They're really beautiful!
My thoughts:
Poshmark - seems to be less about vintage bags, more about social networking and recent fashion. Limit of 4 pics. Their 20% commission seems high, but on the other hand shipping is a breeze. Buyers seem to expect sellers to negotiate. Lots of "Followers," but no sales for me.
eBay - I've had good success selling properly ID'd, properly lit and photographed, vintage bags using Buy It Now (Immediate Payment Required). The main advantages I see here are: 12 free photos, discounts on shipping (esp. for Top Rated Sellers), and the unsurpassed exposure you get.
Etsy - was my second choice for selling, but drawbacks included the 5-picture limit, listing fee ($0.20 every 4 months until item sells), and less of a discount on shipping compared to eBay. My items took longer to sell here. One advantage is the lower "final value" fee - 3.5% compared to 10% on eBay.