Heyho!
I think the Boomfestival will be one of the greatest events this year in trance, i personally have the strongest intention to go there. This will be the first time for me, but i only heard the best things about the previous ones, and as i see the global trance culture's fast improving (booming:)), i can imagine, it will be amazing this year. If someone has ever seen more than ten thousand nice people dancing together, they know what i mean... If not, come and try!
And there are really great things for Bulgaria... Disham and Vataff Project will play live in the chillout, i think we have to see them there!!
If you take some advices for the travel... Portugal is more than 4000 km from here, i wouldn't try it with car/minibus/bus. I am sure, there will be at least 20 people coming from BG, it could sound good: let's put the money together and rent a minibus, but if you make the calculation, it won't be cheaper then by plane. Not only the petrol, but the motorways are expensive in Italy, France, and there are other things to pay as well, problems might come up in the long way.
There are other options. First of all, the European football chamionship will have finished long by then (July 4th is the final), the ticketprices will go back to normal. It will be still peak season for Portugal, it's summer anyway.
There are new airlines, low cost - no frills airlines, like the famous Ryanair for instance, which unfortunately doesn't fly here yet. At this time there is only one operating here, Bexx Air (
http://www.bexxair.pl), but by the summertime surely there will be more. You can find extra fresh info about the new low cost airlines at:
http://www.attitudetravel.com. It's a site collecting all info from every country reachable by low cost airlines.
From here there won't be any chance to reach Portugal directly with these airilines, but you can always combine the flight with ground-travel, trains, buses, hitch-hike, lift-service. For example you can fly from Sofia to a german city with Bexx Air for 60 Euros, than take a lift-service (
http://www.mitfahrzentrale.de, or others) to Portugal or Spain, or hitch-hike from there. You can also go to Greece and fly from there, they have much more airlines.
With these options you can come and go for no more than 150 Euros to Portugal, it's still not very cheap for a BG salaries, but cheaper than an Air France or Lufthansa.
And if not, check out for festivals in Bulgaria, maybe there will be some nice ones:)...