We've been in the data-scraping and data-mining business for 20 years.
You are right, this is trivial, provided you have a guaranteed format for the incoming data.
The quickest way to implement this would be, as you suspect, with HTML and some sort of scripting language like Perl or PHP.
You upload the file (or files) in question, get back a new file of your comma-separated lat/lon pairs, or display the data to your web browser tab for copy and pasting.
Our hourly rate is $200, but we could get this done for you with our flat rate project minimum which is 15-minutes.
The exact function you want to be good friends with, if you end up using PHP yourself, is preg_match_all().
Thanks for your time, and have a great day.