No joke...I heard Dale "Snort" Snograss, the guy flying the Tomcat in your avatar, was trying to buy a dozen Tomcats, I think to fly as an agressor squadron under contract to the military or something like that...so it's certainly POSSIBLE you might buy a Tomcat...for real!
Down in Florida, there is a company that already does it...they fly A-4s. Nice gig, mixing it up with Navy squadron guys, and getting paid for it.
Flightsafety, who does work with instrumentation testing, has several F-100s and A-4s they use on a routine basis, they have cool white and blue paint jobs. Once did a YA A-4 in the Flightsafety scheme.

Fellow I know works for a company that was just given an Apache on loan, so he could test power-line avoidance systems they are developing.

There were some nice Mig-29s for sale on ebay, all crated up and here in the states, ready to be delivered, on ebay, a few years back. Pretty good deals, too!