I posted a thread earlier regarding this, but in Borovets we ended up paying 15 levs for minor repairs, edges and waxing.
Most places gave us a sob story on how bad the scratches were and it woudl take hours, but if you take the road past the bottom gondala and turn left, there is a shop there that is honest and do a pretty good job for the 15 levs.
i have bought a kit to do it myself cost £50 got instructions and seems straight forward,i know here it costs about £20 to do a board hope this helps
chris