I'd possible risk a cheap cat N, rear ended. The thought of a front end with potentially airbags, suspension and steering components, aircon and cooling system all being replaced with parts from a scrapyard on someone's driveway scares me. I could live with a slightly crumpled boot floor to save a pile of cash.
My young neighbour had a go at one years ago, it was a Vauxhall Calibra, and the finished article didn't look too bad from a distance but when he proudly showed me round it he explained that although the replacement bumpers, panels etc were quite cheap the bits of rubber and plastic trim that clipped into them weren't - so he had "replicated" some of them with carefully shaped body filler!