If you want and can afford new, I would urge you to stick to Beck (chines1 above) or Vintage. Both are known for their support and responsiveness before and after delivery. That cannot be said for other manufacturers.
If you're looking for used, Carey (chines1 above) and Greg Leach (Vintage) are good resources for cars that have been properly vetted. Also @Alan Merklin and @Troy Sloan sometimes have cars for sale. They are frequent posters here and can be trusted.
We might be able to assist you more if you provide things like budget, timeframe, and desired features. Also, be advised the these are not like a late model Miata in older looking clothing (although the new Beck version is getting closer and closer). Depending on chassis, drivetrain, etc., you are basically getting old technology and the charm/hassles that come with it. Some folks love that - others not so much.
I'll reiterate what Carey and Wolfgang said - beware of scammers!