My country has cash so i go to you and tell you, Ok sir will you sell me, lease me or anything similar your land for 1billion $. You rub your hands thinking how good deal that was but in fact real value of your land is lets say 100billion $.
Free & fair trade leaves both parties the richer.
The value of a good is what the market settles on. If you sell your land for 1 billion, that's what it's worth to you.