Ok, the next HP swap is being hosted in a week or so! Keep an eye out in the swap signup area! It will be the HP Diagon Alley/Hogsmeade Swap. The shops/stores of those two areas (I'm sure you could include Knockturn Alley also!) and their merchandise.
Good luck with finding magnetic snaps - I'm enamored of them, but no one in a one hour radius of me sells them. I guess I'll have to break down and internet order some.
You're right, velcro wouldn't be so tasteful. What do you think of doing some sort of magnets on the interior of the bag and the flap? Something that wouldn't show on the outside? I'm not exactly sure of how you would do that, but it sounds cool, eh?