about 7 cents per KW in Serbia, not sure about Bulgaria, it might be more like 8-9 cents here. Serbia has cheaper energy because it is friends with russia, and the duties from russia are lower for non-EU countries buying it, plus the fuel import excise is smaller. I can't be certain, since I haven't actually researched it, but Romanian oil is also quite cheap and I think it's used in power plants, in several countries nearby, and, of course, a lot of the wells in Romania are russian owned as well.
One thing that is different now is that bitcoin is pretty much impossible to profit on. However, right now, it's about 130 days ROI on average if you use a service like nicehash, so in 3 months time I'm at break even. But I mainly set the miners up for cashflow, and if they manage to pay themselves off, that's a bonus.
Are you mainly able to get by over there speaking English or do you know a lot of different languages?
I mainly speak english but I spent some time learning bulgarian and I can get by easily in shops and taxies. I advise that you don't consider migrating unless you first make some friends who will help you navigate the bureaucracy involved in migration. It's cheap to get registered and be allowed to stay, but you will bump into a lot of people who have no idea, because they are natives and have few expat friends. The bureaucrats generally don't speak english and it's advisable to have a translator with you when you are doing it.