There were a total of 811,634 Mazda RX7s made between 1978 and 2002. On average these vehicles are actually relatively cheap, with a used price of $11,000 to $37,500. Older Mazda RX7s will be cheaper than newer models in general, despite their relative scarcity.
If you really want to purchase an RX7, you’ll need to find a model that was manufactured in 1995 or earlier in order to be an owner in the United States.