Hi Lee,
yes there is a cheaper chance. You can take the bus fom Sofia to Samokov and from Samokov you can take the bus to Borovets. The only disadvantage is it takes you some more time and you have to get the last bus to Borovets at 7 p.m. otherwise you can use a taxi from Samokov which nevertheless is cheaper than a taxi from Sofia to Borovets. Nevertheless we just can affirm using borovets-pms. They are the cheapest and very reliable. Have been using them for some years.
The buses leave from busstation South every 30 minutes between 6 a.m. and 8 p. m. and cost 10 Leva per person. The bus from Samokov to Borovets costs you 2 Leva per person. For transfer from airport to the busstation you will need about 10 Leva. So if you are willing to investin time, you can save some money.
Lee, 67 euros is for the taxi, you can have up to 3 people share so you share the price, its not per person. If you want to save a few pounds and wait for hours do the bus, otherwise I recommend the transfer company borovets-pms
Yes, it's 67 euros for the return transfer for up to 3 people sharing. It is actually very reasonable - even if there are only 2 of you it works out at something like 16 euros per person each way.
Email Balkan-pms and ask them to tell you if there's anyone else arriving on your flight. If so you can share a larger vehicle with others.
Are you sorted? When are you coming out? We know people out on most days over the next 2 weeks and the cheapest option is to share transfers with them as the price reduced the more people are on the transfer.