Cheapest frontline property I know of in Europe is Albania, as discussed in this thread:
http://www.propertycommunity.com/forum/other...tment-20k.html
Personally I still think that it is a little bit too early for Albania. The infrastructure isn't there at the moment. Sure the prices can only increase, but I don't think that you will see the same rapid price increases that, say, Montenegro has seen over 12 months until Albania gets more established as a mainstream tourist destination.
While in most emerging markets which have potential for growth in tourism frontline property will be easier to rent and so will have the best price growth, I think you need to look at the potential of the market as a whole.
For example, you could probably pick up a nice piece of Eritrean frontline property for $5,000. But would it be easy to rent out? No! Is it going to see rapid price growth any time soon? No!