House under contract and owner sold it

[Debra N.]

We have a house under contract (going on 3 weeks now).  It is a rat trap and a hard sell, but we have an investor that wanted to see it.  We called the owner to make arrangements and he said he sold it to his neighbor this week.  

Now the contract was for 8500 and we reduced the sell price down to 10,500 and finally had some interest in it, so the wholesale fee was going to be small, but that's not the point !

Does this happen to wholesale contracts a lot?