The 370Z isn't what I would call cheap. It sells for at least £30,000 once you add a few extras, you can get a BMW Z4 for the same sort of money. I imagine the Genesis Coupe would be below £25k with a decent spec if they sold it here.
In US, as BlahBlahYouToo mentioned, fully loaded 370Z is under $ 40k and base Z430 (3.0 NA N52) is $ 46k. If you want a performance on par with 370Z, you should consider Z435 (3.0T N54), which starts at $ 52k. Probably either we are ripped off by Germans, or treated too well by Japanese I guess. lol
For Genesis Coupe, Hyundai has been priced 2.0T starts a little cheaper than base upper level Sonata (V6/2.0T in US) and 3.8 starts a little more expensive. What's MSRP of upper level Sonata over there?