Looking for Developers and/or advice

I work reselling products from Craigslist, Facebook Marketplace and Offerup. There is a lot of competition in my area so the first person to reply to a listing when posted usually is the one to get the product. For me to be successful in this, I have to sit and click refresh on web listings all day in order to be the first to reply. I am looking for some sort of software or webservice that after setting specific parameters, It will send me the new listings via SMS, email or push notifications to my phone so I can quickly send my offer and be the first response. I'm looking for ideas, advice, or a program designed from the ground up.

Also, eventually I'd like to expand the service and use multiple cities sending listings to multiple numbers, 100+. If it needs to be a standalone program ran on a dedicated server that is fine as well.