I think Kiwi1 is right about getting the best rate from the cash dispenser. There are several in Bansko, also at the ski-center/gondola. The only disadvantage is that from most of them you can only withdraw up to 200 leva a day.
Hi, my husband and I are going to Pamporovo in January/February and are staying at the Perelick - does anyone know if there a cash point near there to withdraw any Lev ?
Some M & S stores have a foreign exchange booth in the store.
My one here in Belfast has one - they said just to pop in a couple of weeks in advance and I could pay cash for my Lev. You don't have to be an account holder (so I'm told).