That will give you a good idea on how your property will do.

I've been toying with the idea of adding an ISA to my sales business.

I guess the idea is to use the equity from one property to purchase the second property, and so on.

I am trying to get an estimated idea of the cost of this project.

I love the idea of a tiny home. 

Great idea. 

As a courtesy it might be a good idea to let that agent know regardless.  

The idea of real estate investing both intrigues and terrifies me.

If you like the idea of a self-directed HSA like @Kaaren Hall mentioned check out providers like Accuplan and IRA Financial Trust. 

For example, if you are in a 24% tax bracket and the house is valued at $200,000, your potential tax savings might be around $48,000 (24% of $200,000), but that's a rough estimate and assumes you're itemizing.It's always a good idea to consult a tax professional to ensure you're maximizing your deduction and following all the necessary procedures for your donation.