How do you smart folks evaluate land?

[Tommy Burch]

Hello and thanks for the help!

First post here.

Summary: My brother lives in another state and he just had an offer accepted. This will be his families primary residence. It is waterfront. My brother and I are close. The house he bought has two lots (on either side of him) that will be listed soon. Both waterfront. I have over 2M in stock market and zero debt (no mortgage, income is variable but around 80-200k per year). I am considering buying one of the lots adjacent to his new home and eventually building a vacation home here. I could rent out this house when not there but mostly this would be a consumption item. I love to fish and It would be really cool to be able to visit my brother and stay in a house right next door. BBQ while looking at the water, fish from our backyard etc. 

Questions:

1. How do you determine the correct price for land?

2. what questions would ask?

Thanks!