Depends how much you eat and drink and shop! Personally I just take £100 to get through first couple of days and then use cash cards to draw money out.
I do drinks / snacks / lunches/ essential bits and bobs (hats, tissues, nail files, ski storage, taxis) (Days) and Bibblyb0bs does nights... and I tend to get through £300 ish in the week. Bob apparently spends MUCH MORE than me - and it ends up in a row there.... Seven more weeks to save my pennies...
I take some Levs, about £100, and some sterling (To get changed at the bank in the bottom of the Rila (Borovets)) and then use my cash card as and when. As usual you spend loads in the first couple of days sorting stuff out and then it tapers off.
we don't drink much so took £100 each last year to pamps, only spent about £60 in the week! May cost mroe with these price hikes... i remember a bottle of water on slopes being 2 leva, this was at the bottom of the green run and was for a 500ml bottle... may be more now, jacket pot was 5 leva and was really tasty. We enjoyed the hotel food so didn't go out to eat much, just 3 times.
i think £200 for one person will be more than enough but really does depend on how much you intend to drink!!