This next car is either a really expensive project that needs thousands of dollars of work to get it on the road...or a really good deal on a jet engine sitting on a "vehicle" chassis. Not sure which yet...but I'd take it for a test drive. Find this 1970s Jet Dragster Allison J35 here on eBay offered for $10,000 buy-it-now. 
Okay, this is easy. I've found a 60's era Boeing gas turbine engine on ebay and you need to find me the vehicle that it should go into. A Prius, a Pontiac Aztec, a Tesla, a Model A -- it really doesn't matter the price or cost or value of said vehicle -- you just need to justify your decision. Find a good home for this Boeing 502-7 Gas Turbine Jet Engine here on eBay bidding for $4,500 with a few hours to go, located in Punta Gorda, FL.
Earlier this year I had the good fortune to visit the land down under for a business trip and I can tell you it was a magical place. The scenery was otherworldly and the cars were also from another dimension...but this next car is not just another fast saloon car, its a bloody ripper. If you don't want a car that requires a checklist to get going in the morning or could give you third degree burns if you turn left quickly...you probably should look elsewhere. Find this 1991ish Holden Commodore Jet Car here on ebay
currently bidding for $10,000 AUD ($7,853 USD) located in Enfield, South Australia with 1 day to go. Tip from Lars W.
The EV-1 might be the first car to wear the crown as a modern electric car from a OE manufacturer, but the truth is that electric cars were very common in the early days of the automobile. As time marched onward, the speeds and distances required outpaced 1920s battery state-of-the-art, so the electric car went into hiatus, only to be revived in the 70s when technology allowed it. But not OE technology...small guys in their garages and hacks around the world started building things like this 1980 Jet Electrica 007 offered for $4,000 in Millersville, MD. Tip from Chad in MD.
Have you ever been cruisin' down the I90 outside of Cleveland and sorta thought you heard a jet, but the noises got uncomfortably loud, to the point you fully expect to see a 747 landing gear in your rear-view, expect you don't...what you see is a red Porsche 928. And then it blasts by you in a fog of Jet B and testosterone...suddenly you want one yourself. Find this 1984 Porsche 928S with Boeing 502 turboshaft power here on eBay bidding for $5,500 with a day to go, located in Painesville, OH. Tip from Hunter.
The third generation Mitsubishi Eclipse was a huge disappointment for speed junkies and Mitsubishi performance enthusiasts when it was released for the 2000 model year. Gone was the peppy turbocharged 4-banger and road-hugging all-wheel-drive, in its place was a ponderous sloppy suspension and V6 power mated to the bloated Chrysler Sebring (ST-22) chassis. Just about the only way you could possibly salvage the actually-not-that-bad-looking 3G Eclipse is with a General Electric Turbojet mounted in the trunk. Like this 2003 Mitsubishi Eclipse found here on eBay
with opening bid of $24,000 reserve-not-met with 5 days to go, located in Reno, NV. Tip from Neil.
listed for $1,100 buy-it-now. 