You can still purchase in $ even if you're from the UK. In fact, you get better value for money doing it this way due to the exchange rate.
When I made the VMWare to Parallels upgrade, it converted to roughly £22 from $34.49 (they add tax on to this at the next payment stage) Makes you wonder why they have the option to begin with, can they just not adjust prices relative to exchange rates?
Subsequently I asked for a refund later on down the line, but that's another story again!
