I'm back. I wound up taking it with me, and getting it filled was no issue. The dive operator owner was certified to do hydro tests as well, and with the newly certified sticker, there were no issues. I agree that it will vary by country. Didn't charge me either for it. Since I did 8 dives with him, I think he did okay.
Dive gear is often cheaper in the US (from my observations, I'm sure there are exceptions). I did look at the price of the same sized pony bottles, and they were not cheap. Since I was taking all my own diving gear, I just opted for the second suitcase, paying $100 for one way, 75 Euros for the other. That was still cheaper than a new bottle.
Noted when I come to the UK to dive the Scapa Flow (though I'd either be on a rebreather or twins).