As far as I know, there are only 2 manufacturers of Pellet Boilers in BG, the majority come from either the Czech Republic or China.
I don't know if the Italians actually make them or rebrand them. I say this because I have recently approached Italian companies for handmade stairs and Sofa's only to find they are not actually made in Italy but imported from China/Czech and "built" in Italy (In other words fitted the plug and company logo) in a small workshop. The law in Italy is that you MUST say where the item is built, not where it came from (Same scenario in France). Needless to say , buying the same stairs direct from China myself cost 60% less.
Anyway. I do have the suppliers contact details here for pellet boilers who will provide you with a good standard boiler, installation, and after service. Alternatively you can buy direct from any of 50 factories in the Czech republic if you ask them nicely, but the price differential is about double by the time you have got it to BG. IMO buy a Czech one in BG if you just want the one.