I can use a kick in the *** to stop accepting these things, and I bet you could too.

Your best bet is borrowing from your relatives. 

If you were to go to a third party lender on this size deal, the loan would have personal guarantees so that inherent in the seller financing is the concept that to sweeten the deal, the seller is providing you an economic advantage hence the higher price.

Lucky for you, you shouldn't have to go very far because there are plenty of agents here in your area who know how to think like an investor because many of them are investors.Your agent will size you up in a sense to ensure you're a serious investor with the means to purchase, and not just an eager window shopper.

I am assuming that your lot size is about 35ft and therefore you need to allow for 7ft in the back.

I would be willing to bet he doesn't need your buyers, as he has a $25k marketing budget. 

I live in Tulsa, OK.Put it out to the universe that you are looking to increase in size and you need a partner. 

And it is not the material, labor, mark up cost but rather how much will it cost for flooring, painting, etc. to get put into place.For those buying materials for their contractors, I bet they have years of experience under their belts before doing business this way.Example: how much ceramic tile do you buy for a 10'x11.5' room?  

Don't get blind sighted by Mountain House new big. and cheap but look for right sized work horse properties that will rent in any economy and enjoy future demand.

@Upen Patel is a mortgage broker...and I bet he has a lot of information on the 203k loan.Also try tagging people in the responses so they see it.