What Huge Mistake Not To Make When Learning To Wholesale

So my partner and I purchase a lot of homes for our turnkey business.  A lot of the properties we purchase come from off market listings in which smaller wholesalers will find property and then bring them to us to determine if we will buy it from them or not.  We have a reputation of buying all  cash and closing very fast ( sometimes within the same day ).   

So today I met a new wholesaler who I have actually known for a while but has never brought me a deal until today.  I meet him at the home and after we go outside to talk about the property he tells me he has it under contract for $28,500 and wants to sell to me for $32k.  I agree but then he tells me his partner just texted him and said another local TK provider is also willing to pay $32k so I say then I will take it for $33k.  We shake hands and he then tells me I got it and will send me a contract shortly.  

*** Here Is What You Do Not Do, Ever ***  I get a call from him a few hours later telling me that another person they had told about the property has agreed to buy it now for $36k and basically told me they cant pass up the extra $3k profit. I keep my cool and basically told them that though $3k extra seems like a lot, it could actually cost them more long-term.  If you shake someones hand and tell them they are going to get the home, you give them the home.  Otherwise your word is no good.  There are a handful of real companies here that are cash buyers and you dont ever want to ruin the relationship with them.  You simply tell the " higher bidder that came along " that they missed out on this one.  They wouldn't care and you would still sell the home.