BBC DVDs are always expensive, but they're usually cheaper to import if you have a region-free player.
The reason they're expensive, in general, is due to the fact that the BBC is a partially government funded, non-profit organization (should I have used an 's' for that word?) so all of their profit goes into developing new programming... so they try to make a pretty good profit, in general.
I might have to pass on Extras, atm, but I've been thinking about starting a collection of classic Doctor Who DVDs... but, WOW, those are quite an investment. Usually 4-6 episodes for $15-25!? And they're not much better in price from Amazon.co.uk...
...maybe when I'm rich!
Also, token2k6, you can't stand British accents for more than half an hour!? Xenophobia, much? I'm sure there are a lot of people who can't stand all different kinds of southern accents, too... but you usually don't see them whining about it! Also, you're missing out on a lot of REALLY good TV, btw.
I'm curious, which British dialect bothers you more: general London or Cockney? There are tons of others, just so you know.