I've never heard the 25% thing before, but any difference between FMV and sales price would technically be considered a "gift" with potential tax implications for your parents.You can avoid most seller costs as there's no reason to use agents in this case.As an FYI: I always recommend avoiding a FHA loan, if you qualify for a low-down payment conventional loan.

@Tom Stevensonyes, when I BRRRR I typically use my own cash for the down payment, and a hard money loan for the balance. 

Attorney FeeHolding Costs:1.Loan Interest Payment 2.

I've been doing a deep dive looking at cash on cash return for various down payments and expenses on properties with a mortgage.

This cost is going to be the bulk of your monthly payments for mobile homes in parks.

go to lots and lots of meetups.2. talk to those HMLs and find out what their terms are.3. save up enough so that you have a down payment, reserves, and also enough in cash for the hold period. 

So call it $60K for the down payment, and another $8,200 for reserves.

@Russell Brazil Although, Russell brings up a good point, I have personally read the Fair Housing Act several times and have never seen anything in there about it being illegal to discriminate against payment source.

What tools or processes have you implemented to estimate rehab costs more accurately and avoid scope creep in BRRRR projects?

I know there are pros and cons to each side of this question but is it better to self fund your first deal or to put a down payment for a real estate investment loan?