I suspect the Pfullendorf area is too far away for you. But 2 neighboring plots are currently still in the hands of a realtor (most likely related to the mayor, who had 5 plots...).
Oh, I thought that was Schmalegg itself :D There is absolutely nothing there in terms of shopping facilities, doctors, and CO. and it costs 450€ + 200€ for the rest undeveloped. That is expensive. 250€ is totally fine.