Did I find a potential gold mine?

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Hi all, 

Sorry for the odd title. Haha. Not sure what else to title it. 

I was browsing a tax map to look at a lot of raw land I will be purchasing from a family member for a personal residence. I decided to view the other undeveloped lots on the tax map as well. Intermittently, lots were purchased by a builder for $50,000 in July of 2021. The lots are only assessed at $3,500. Most of them were purchased for less than that between 10-20 years ago. Could this be a gold mine for wholesaling to a builder? 

Thanks!