I agree with Qawra,
As a foreign prop owner, the only place to guage what something will rent for, is to check the local sites; just like you would check the Herald or daft.ie for the irish buy2let market.
Guaranteed rental schemes are an ABSOLUTE SCAM, 100% of the time. You are in effect (as is mentioned above) paying your own rent. The only place i've seen this work is in France, with long-term leasing.
Also, never believe a word an Agent tells you, including Eddie Hobbs; the sound-bytes are good, and in the main actually quite true, but you need to do your own research. If you have $dollar-signs$ for Cap Appreciation, and a wad of cash to spend, then you will be shafted. Taking candy from a baby.
Go to the internet, and find english-speaking newspapers in the relevant country. If the irish are buying property there, it will almost certainly have a DB of articles on property, and most likely a property section.
these sites also show property for sale, at the local price. Everything in eastern europe sells in price per sq.meter. You will find the local price differs from the agents price by about 20% usually, sometimes much more. This is a fact of life with all apartments sold to foreign interests.
The Property section of AAM has some good threads on foreign property, eastern europe in particular, with some good posts from people who have been down the road, and learned the lessons. Worth a search.