I think a better term than poor man's supercar would be a "budget supercar". A budget supercar to me is a z06 or zr1, viper, and gtr. These cars can keep up with the fastest and most expensive supercars while being far more affordable, relatively speaking.
What about the M3? Puhlease, an M3 couldn't even keep up with a Mustang GT at laguna seca. Is the M3 anywhere near a supercar? Don't make me laugh.