Oh yeah, I've done that before and on the next order they will complain that the bill is higher than last time.
"Wait, it was $125 last year and it's $145 now why so high?"
"Well, I forgot to charge for the numbering on the last order so you go that for free."
"Can you still do it for $125?"
:l
Yup.
I actually had a guy ask for a discount because he knew what I charged a friend of his. Word of mouth referral and all.
He asked why so expensive. I told him to look at the other 3 estimates he had just referred me to (he offered and I did not ask) to which I was well under the lowest of the 3. I said "you got my best price for the job you want".
He said "You only charged my friend X amount"
After a half hour of explanations he was made to see he was asking for much more with larger equipment. 2 extra duct add ons and his system was bigger. I left him with my price. I got tired of dickering with him.
A week later he called and said if I cut $500 from my price he would give me the work. I said no to the hell no. Hung up and blocked his number.