If I were to do a traditional VA loan, the loan would be close to 7%.Below are what I understand to be the numbers so far:Seller purchased the property in DEC 2022 for $1.13M (owned for 2yrs)Current estimates are Zillow= $1.26M/  Redfin=$1.323MOur agreed purchase price is $1.25MSeller financing would be $120k @ 8% for 3yrs.No commission cost.Small percentage of fees/ costs in the tune of 1.5% of loan amount.Let me know what you think and if you need any additional info.

And then a client's new build in the suburbs of Denver that cost $800,000 and should get around $85-$90k, so 10.5-11%. 

Quote from @JD Martin: If you have found people willing to lend you - someone with I assume no experience doing this, since you're here asking the question - 100% of the costs of such an endeavor for half the profits, you have found a gold mine and should look no further.

We have a reasonable cost of living and properties are significantly less than CA.

The guy on Youtube that boasts about buying properties with no money out of his pocket and using other people's money from his "community" to pay for closing and carrying costs, said in a video in June that he had 10 Due on Sale called in AZ alone from Jan 2024 to May 2024.

The land is being sold as the investment is costly with all the illegal dumping and clean-up cost.

By my estimates, pricelabs cost me approx $25K last year in lost revenue for some of the same reasons you've listed in your post.

Are there risks or hidden costs I might not be considering?

The reason not to upgrade, is that you won't get that much more income for the cost of the upgrades.  

At the end of the day, you won't make a pile of money, it will cost the developer more money than if they were just reasonable, and only the lawyers will be happy.