The "penalty clause" really helps in this case.That said, you have to have enough leverage so the contractor accepts the clause upfront. 

Sadly, many of the sellers don’t want to pay the commission and are doing thIs wIthout an agent I would have seek compensation from the buyer.

Statistically, if we just pay it our expectation value is to lose $100.If we venture into the grey area and don't pay it our expectation value is to lose {[$100 PLUS penalties and interest] TIMES [probability of having to pay it]}If our penalties and interest run 25% total, then we are looking at {[$100 + $25] X [probability of having to pay it].

Before that, I would caution you to seek advice.

Assume an accredited investor and no securities law issues for simplicity.1) Homeowner pays for a legitimate appraisal.2) Homeowner grants the right to Investor to receive 10% of any appreciation above the appraised value when and if the house is sold.3) In exchange, Investor pays the homeowner an amount equal to 10% of the appraised value, with 20% down and the rest on an interest-only promissory note held by Homeowner.4) The note bears interest at Prime + 0% and does not have any origination fees or prepayment penalties.5) The investor gets credit for 10% of the eventual net proceeds from sale with the net being 10% of net sales proceeds less the remaining balance of the loan.6) If the investor defaults on the loan and fails to cure the default, the claim on the equity is forfeited.7) The homeowner remains fully responsible for costs of maintenance, insurance and taxes, but this is offset somewhat by the interest on the loan and the cash received upfront.8) Presumably if there is a gain beyond the homeowner's basis, there is no tax for now unless the proceeds exceed $250k for an individual or $500k for a couple.

If the landlord fails to do so, then the tenant can withhold rent and seek other remedies.

Mostly likely, if you've paid the bill and then get a reduction, they'll send you a refund.If you don't pay your tax bill when it's due the government charges 1 and 1/2% per month plus penalties and fees. 

I would recommend while you're searching for a good broker you develop a set of preferred criteria you're seeking.

Should they get such an offer, then they can decline mine with no penalty. 

 Targeting 3-9 deals within a $100K-$500K price range over the next 18-24 months.  Any great advice for a newbie (especially on topics directly applicable to the Houston market) would be much appreciated!  :)