However, I can substitute another buyer.

we are usually willing to owner finance to a buyer with some down payment ( I've actually done as low as 2% down but this was an exception) and good credit - the good credit can be substituted for some down.

Yes, the contract is a substitute for a listing agreement.

Nothing can substitute a hard estimate based upon historical numbers.

Also keep in mind that most people (not all) that choose to do much/most/all of the rehab, at least at the beginning, are substituting sweat equity for liquid equity.

Supply, demand, consumer and producer surplus, dead weight loss, price equilibrium and availability of substitute goods are what drive prices.

(A recorded trustee’s deed [or similar alternative] confirming the amount paid by the grantee to trustee may be substituted for a Settlement Statement if a Settlement Statement was not provided to the purchaser at time of sale.)The preliminary title search or report must not reflect any existing liens on the subject property.The sources of funds for the purchase transaction are documented (such as bank statements, personal loan documents, or a HELOC on another property).If the source of funds to acquire the property was an unsecured loan or a loan secured by an asset other than the subject property (such as a HELOC secured by another property), the Settlement Statement for the refinance transaction must reflect that all cash-out proceeds be used to pay off or pay down, if applicable, the loan used to purchase the property.

The expensive drapes are substituted with bare or plastic blinds etc.

They say "could you substitute some home cooked meals instead of the keg? 

We will not even go over hedonic indexing, substitutions, etc.