I have no problem spending £36ish on a ticket to ENO for a couple of hours watching an opera and think I've got a bargain. (Depends on the opera, obviously...)
But if a DVD costs more than £2 or £3, I go 'Hmmm, that's a bit expensive!'.
Partly, it's because there's a second-hand market for DVDs (have a browse of Amazon or CeX), a rental market and imports, but also because today's £29.99 special collectors edition disk is tomorrow's 'free with today's paper' promotional item - and at least two of those are down to the studios.
I had a £20 HMV gift token from some survey recently and had two looks around their extensive collection. I couldn't get the purchases up to £20. The money might have been free, but even so, '£5 for that? No thanks!'
In the end, I gave it as a birthday present to my nephew who was happy to spend it :)