Hi.
I've just come back from Malawi having done some research about this and having looked at a couple of lodges that are for sale near Nkhtata Bay (I can supply you the details if you're interested). After visiting these and seeing the prices that others had sold for we ended up buying a hectare of land (lakeshore) which we are going to develop. Although I haven't done the full costings for this, preliminary estimates suggest it's going to be a lot cheaper than buying a place although obviously a lot more work.
Although it isn't possible for a non-Malawian to purchase the freehold it is easy enough to purchase the leasehold (as long as you can find and verify the landowner)
If you need any more info then let me know
Cheers