Rural properties in any holiday destination tend to be a more attractive option in many ways for foreign buyers, but this realisation only comes after a few years of living by the beach with the crowds and the lack of tranquility. In general, the vast majority of buyers want seaside property, and the rural alternative (attractive and all as it may be) will never comprise anything but a tiny fraction of the overall market. This is the reality, and investors ignore it at their peril.
Without the over hype of the coastal and ski property market in Bulgaria, it is possible that the rural sector that you promote might have survived in its niche, but the collapse of the mass market has undoubtedly dragged down the rest of the real estate market in Bulgaria.
Bulgarian coastal property had a market niche, selling to Bulgarian, Russian and Ukranian buyers, but it was never going to be able to sustain the business generated in the UK, Ireland, Holland etc in recent years. Pumping up the prices by one to two hundred percent, and further inflating the market with the guaranteed rental scam, created a "perfect storm" that brought down the market and the rural market with it, and it won't recover any time soon.