I assume you're talking about Amsterdam Seed Supply. Probably old seed stock if I had to guess. The fact they still have Dinafem in stock suggests this considering Dinafem hasn't been around in a few years now.
There is plenty here in the US though. You don't need to order from across the pond unless there's something very specific you're looking for. Let us know what you're looking for, and I'm sure you'll get some solid advice pointing you in the right directions.
Cheers