I would suggest that while a sizeable number of people are buying property in Bulgaria, very little of it constitutes investment, i.e. property that will give a reasonable return over a 7 to 10 year period. In fact, anyone buying some of the overhyped garbage on the Black Sea coast or in the mountains is almost sure to lose money; they are paying in some cases up to four times the market value, and there is no local demand even at the real price. In addition, the market is driven by multiple layers of agency fees, with up to 15% and sometimes more of the price constituting agency fees, on top of the already inflated prices.
Investment in Central and Eastern Europe is mostly in Hungary and Poland; you pays your money and you takes your choice! Hungary has settled down to become a stable market following a rush of not always sensible purchasing by foreigners (Irish/English & Spanish mostly), and good value is to be had in good residential areas in and around Budapest in particular. The city seems set to grow further with the inevitable drift from rural farming to city working, and an addition very substantial pent-up market of adults living with parents should enhance the demographics over the next 5 to 10 years as increasing salaries and lower interest rates allow them to move out and buy places of their own. Recent hardline stance by the government seems set to turn the economy around, and the market has read these signals well, contrary to the prophesies of the doomsayers. At the end of the day, the capital is one of Europe´s finest cities, and most investors are now competing with local buyers in a sane market. Looks positive.
In Poland, returning funds from emigrant workers are stirring up the market in a few places, and as with Hungary the economy seems set to grow steadily if the government were to be led by some visionary politicians -- do the current two qualify? If this issue can be overcome, Poland also looks like not a bad bet, my own preference is for Krakow with its strong tourist economy and good local demand. Avoid anywhere in the Silesia area, where rationalisation of the coalmining industry has dumped tens of thousands on to the meagre social assistance and created an almost third world economy in this area. Don´t even think about buying around here, no matter how cheap it seems!
East Germany is attracting a lot of funds, but its a dangerous market for many reasons. A falling population (the government is effectively paying women to have children in order to try to correct this trend), and a drift to the west part of the country, coupled with horrendous problems with title dating back to pre-communist times, makes the former East Germany a place to avoid. This also includes west Berlin, and indeed much of Berlin unless you are well clued in on local nuances.
The Czech Republic is still ok, but few bargains to be had. A sizeable minority of investors are hitting Slovakia, mostly Bratislava and some of the ski areas, neither of which have great prospects. The best bet here is small commercial units close to the big development being bulit by Ballymore Homes on the former City landbank in downtown Bratislava, but these are scarce and hard to find.
Riga is not bad, but a lot of money from Irish investors has gone to cheap apartments in old communist blocks, which offer poor long term prospects. Good downtown stuff is expensive -- you will do better in Budapest for less money, and with better prospects.
Very little money going to the gem of them all -- Romania. Full of potential, avoid Bucharest and stick to Constanta, Cluj or smaller cities. Good value in land and sites along the Black Sea coast. Big players like McAnthony Realty are now moving into Romania, so look forward to a repeat of Bulgarian experience of seaside apartments at inflated prices, probably with "rental guarantees". Canny investors can still make good returns there, but not from the big guys.
That´s the limit of my expertise on eastern Europe, hope it was of help.