How about a variation on allaboutnice's suggestion: buy an Hermes tie for BH with the money you get from selling it on eBay to sooth any ruffled feathers. You want the 50cm from Paris, so a credit at the local Hermes won't help to pay for the bag you really want. And if you go to Paris with your BH, he might spring for the 50cm, too, so you could keep your eBay gains or even buy a Birkin for your mother.