I wanted to know where I can find a cheap go kart engine near Miami? I've tried Northern but that's pretty much it. If there is anyone that sells old ones or someplace I can get an old used one for cheap.

Northern is about it for new engines, for used engines you need to check out lawn mower repair shops and other small engine shops

You could also see if there are others that might want to sell one by advertising on the following site without having to pay anything for your ad.

The first link is to the main page. The second link is to the "Wanted" section of the site.

craigslist: south florida classifieds for jobs, apartments, personals, for sale, services, community, and events (http://miami.craigslist.org/)

south florida items wanted classifieds - craigslist (http://miami.craigslist.org/wan/)