What are similar cars to the Nissan 350z but cheaper

Well there is the Infinit G-35 but you did say less expensive the g-35 is a 4 seater where as the 350z is a 2 seater......If your just wanting a 2 seater sports car thats cheaper there is the chrysler crossfire..The Mazda Miata , The Honda S2000 just to name a few...

Maybe a Mitsubishi Spyder... I think they're less expensive. They come in a convertible and have 1 minor difference... A rear seating area.