Land buying opportunity

[Jacques Thomas II]

I have a friend that has 3 lots that total 15 acres and she wants a cash buy of 500,000 I’m very new to this industry and I have done a lot of research but I have not researched a lot on land development I want to go on contract to wholesale her land but I do not know how to calculate how much her land is worth I think it is a great deal and if I needed to come down on the price she will go for it because she is in a hurry to sale because she is losing money on it

Any advice or ideas to help me move forward??