Are you saving money at the expense of the site operator by scraping their site for public records, or are you saving money as well as the site operator?
If you're costing them money to reduce your own bottom line without their express written consent, that makes you "the bad guy". Offsetting costs onto an unwitting, non-consenting third party is an unethical approach to doing business.
I interpret your request as a similar problem to "help me with my homework problem". I could dig up papers and studies, but at the end of the day, you need to go do your homework. Reach out to each municipality and figure out a business arrangement with them that satisfies your needs. It's possible they do not wish you to perform this activity, in which case you will either need to violate their intent for your own profit using scraping or accede to their wishes and stop scraping their municipality. That's your homework as a for-profit business.