Purchasing a Property W/ RTO Contract

[Katie Nixon]

Please help me talk myself into this opportunity! I have a handful of rental properties but am still very new to investing.

I have the opportunity to buy a property with an existing RTO contract. I have cash and can close quickly.

See below for information directly from seller:

"2 BR / 1 BA

On a Lease/Purchase Contract for $45,000

Tenants paid a down payment of $1350, Leaving a balance of $43,650

Contract is at 180 months at 10.6% on $43,650 = $485.22/mo

The Buyers are paying $112/week and usually pay every two weeks at $224, deposited into my bank account.As of now, the balance of the contract is $35,300.If, the Buyers pay the remaining 117 months, the total remaining is $56,770.74

The Buyers love the location and the house for it is next door to the wife's parents and want to stay and finish the purchase.There is however some damage to the house of $7800, Quoted by ******. The Buyers do not have the funds to fix the damage and neither do I, so this is why I am willing to pass the profits onto someone else. Also the cost of repairs can be added to the property balance, making the new weekly payment $127.
From the balance owed, this would leave $27,500, I am asking for $15,000 to walk away and someone takeover the contract as the work needs to begin ASAP.I usually have more time to sell a property, but have found myself in a unique position that I cannot control.
Thank you for your time and I hope to hear from you soon"

- How much should I estimate for closing costs?

- Should I negotiate that I'll buy for 15k if they pay closing costs?

Any help is greatly appreciated.