Guess its their way of saying 'can't be assed'
Seems instead of people saying no, they outprice the task so you go elsewhere.
if you don't want the job, just put a high price and up to them if they pay it.
mind you, they might not have the free space, so you might have to pay for a full site. They might have also been abused in the past and now just set a price thats worth their hassle.
Presumed you phoned them directly andexplained the size, length of trailer, etc.