[corin_]

I'm not sure, I always assumed UHT was a bit cheaper but never paid attention (or if I ever did look at the difference I've forgotten).

I just had a quick look at a UK supermarket's online site and both seemed similarly priced with some comparable options being cheaper on one side or the other. Without bothering to spend more time actually doing the maths, and looking at more than one store, it could be that there is a significant difference on average.

In France/Belgium I equally never bothered to check the price difference (I'd still be choosing pasteurised where available if it cost 5x as much), but anecdotally I saw it more in higher-end (most expensive) supermarket chains.