Hi June, we flew to Bourgas this year, and paid £252 each adult, 28th July for 2 weeks, this was with My Travel from Manchester, we then got 3 more flights for the family last minute and had to pay over £300 each because demand was so high. We also got 2 flights with Thompson for £185 each, 30th Aug for 2 weeks, Prior to the summer holidays, before 20th July, you could get last minute flights with Balkan from £60 to £160, as soon as the summer holidays start the prices go through the roof. I have noticed that alot of companies have doubled up on their flights for next year so hopefully the price will come down, try this link with ATM, they do a good search of most of the popular operators, to give you an idea of the cost.
http://www.atmtravel.co.uk/index.phtml?command=default-service&service=2
I have several other links on my website, if you find any other flights, please drop me a line, as i am always looking for cheap flights, hope this helps, Paul