Be weary of the marketing gimmicks of land buying companies. Evaluate the land on itself before committing yourself. What's the true value of the plot on its own. What's the rate of sales of similar plots in the project and surrounding area. How quickly can you sell it off, if it doesn't materialize. What would be the selling price. Start with the worst case scenario and if you are OK with it then at least the best case would be $$$$ for you.
My 2 cents opinion.