dont know if they do it in boro but in bansko you can buy a gondla pass which gets you up to the ski area but wont allow you to use the lifts to go further up.
A ticket for a 2 way ride on the gondola is 18.00 leva adult and 10.00 leva for children.
Alternatively, hang around the gondola and maybe someone who has come down early from a day skiing will give you there day pass???
Fiona