most places seem to be pretty decent. i can speak personally for Ski Mania through Bansko Blog - good service and the gear is decent too.
I donlt think you can pre-book passes less than 6d, so you will probably have to pay normal prices at the gondola on your first day. If you can, do it the evening before - they are supposed to be open late to support this....
E-mail us mate, earlybirdtransfers@skidvd.co.uk
Nightmuffy will get back to you asap with prices... if you want it we can pre-pay and hand them to you on arrival with the vouchers for hire