I am essentially in the property for nothing besides closing costs as the land appraised at $45k.

City has to inspect if I'm not mistaken to determine if threshold is met to where it is a tear down or rehabable.

It would/could be only 15% capital gains tax and yes you could/would deduct all selling costs including commissions and transfer taxes.

That cost me about $1,000 each time. 

Then after the rehab or building is done, they put a tenant into the property and they sell the property at market value to an investor.

Even if it's a total rehab if the land bank has a property in an area where the arv's are substantially high wouldn't that be a good deal or a promising neighborhood for buy and hold.

I am training our son to basically do the rehabs but there is a learning curve.  

This works best when the seller is motivated and open to flexible terms.4.BRRRR Strategy (Buy, Rehab, Rent, Refinance, Repeat)– If you find the right undervalued property, you can finance the rehab with short-term funding and then refinance into a long-term loan, pulling most or all of your money back out.5.House Hacking– If you’re open to living in your investment, you can use an FHA loan (as low as 3.5% down)to buy a multi-unit, live in one unit, and rent out the others.

That's your cost. 

Rehab contractor charged $10K, the online report says $16K.