After meeting a client I quoted them $15,000 for creating a long video with tons of editing for them. . 

Client: Just send us the contract. 

I did, and then spent two hours at their office to learn about the project, their needs, timeline, etc. Then I checked my email.

Client: Sorry, you said $15,000? We thought this wouldn’t cost more than $500. This is way moveon our budget.”

Source: Clients from Hell