This list contains cars under $70k USD
BMW i8 ($55k-$100k+)
Starting off this list is the BMW i8. This hybrid has a standard 3 cyl. turbo with an additional electric engine extending the range by 15 miles. Back in 2015, the MSRP was around $140k. The i8 is a true head turner, but don't expect it to win any races, as the top speed is 155 mph with a 0-60 time in 4.6 seconds. It has butterfly doors plus can be available in a roadster variant, but those easily exceed $80k. The best example I found for sale was $59k with 42k miles on the odometer.
Ferrari 308 GTS ($50k-$68k+)
Being a V8 powered 80's icon most famous for being featured in Magnum P.I., I decided to choose this over the less interesting Mondial 8 because that was more of a family car that Ferrari produced. This however is one of the best Ferrari's for the value. The mileage ranged from 79k for the cheapest, and 40k for the higher priced variants. It's perfect for cruising around town in your favorite Hawaiian shirt with exciting V8 engine sounds right behind you. Back in the day, people would lease these just to say they owned one. However, now they are more affordable and would be a great time to purchase one.
Mercedes-Benz AMG GT ($67k-$130k+)
This selection for the list is near the capped price of $70k. The AMG GT is one of the most sleek and luxurious cars of the 2010's and can easily reach over 180 mph given that it is powered by an 8 cylinder turbo under the hood. On Autotrader, I found a pristine example that has almost 10k miles for a 2017 which is pretty good, for only $67k! The downside is that its the base model but still, it's a really good value for what you are getting. The next cheapest listing however, had almost 41k miles for $69k. Depreciation has hit early, but snatch one up before the good deals are gone.
Nissan GTR R35 ($47k-$72k+)
I could not include this list without bringing up the GTR. It's a very iconic Japanese car and can be recognized by almost anyone who you ask. The average rating for the 2010-2012 model years was a 4.8/5 because of the reliability and practicality which is phenomenal. The modifications and upgrades are never ending and can easily shoot flames from the exhaust with little amounts of tweaking. The V6 produces 485 hp which is a pretty impressive figure for a Nissan. The mileage for ones under $50k tend to reach around 55k to 80k miles.
Aston Martin V8 Vantage ($33k-$47k+)
As stated in the name, this Aston is powered by a V8 producing a modest 430 hp. It may not be the most reliable supercar, but the styling makes up for it. I have lusted over this car for many years in my early childhood because of the simple styling with no weird curves or indents. The only thing to really look out for is the service records when purchasing one. Leather and wood make up the interior of the V8 Vantage to give it a somewhat luxurious feel. Mileage ranges from 55k to 82k miles depending on the price point. It's a great car for city driving and car shows.
Audi R8 ($56k-$140k+)
As most people refer to it as the "Iron Man" car, it is a modern marvel in an art form. Available with 430 to 525 hp, this was the fastest Audi in the lineup from the start of its launch. The pre-facelift still looks up to date when placed next to other super and exotic cars. Used ones for sale have all been driven at least 30k miles spanning to over 105k, showing how much people loved it. If its a coupe or a convertible, it always gets attention at the local valet parking. Earlier variants were optioned with a 6 speed manual but can be somewhat difficult to find for under $70k. Overall, a good value for an excellent machine.