if the customer wants an idea of cost then i normally say it will be between x and y but will quote properly when i see the job, most are happy with that, as it's natural for most to want to get an idea of the approximate cost.
I remember one guy saying "well how many hundreds are we talking about?"
and it made me realize that not all are being penny pinching they just want a figure in their head so they know what they are dealing with.
I think all of us are the same when we are getting quotes for jobs, it's human nature to talk about money and what the cost is going to be, even if we have pots of money.
regards
steve