Yes, you are lowballing because
a) You had to ask.
b) You offered up a lengthy explanation.
That having been said you won't get many customers charging what someone who has been in business 10 to 20 years is charging either, the question I have is why would you even charge less than $30, hell you could have quoted $30, made out, and still been way below the competition.
So there you have it, your whole kit and kaboodle in a nutshell.
You owe me $50