Bansko is 280lev for 6 days (per adult) Thats aprox £103
Try www.banskoski.com for any other info on Bansko if you can't find it here.
I'm sure others will give you the prices for the other resorts
From previous post i gather that there is a price difference between pre booked lift passes and those booked at resorts so
1. approx how much would the difference be for Bansko
2. can you book the lift pass online without getting a whole accomodation package?