I bought an iron horse a few years ago – the rear triangle broke within a couple of months. Because they’d gone bust, the retailer couldn’t sort a replacement, and only offered me a couple of hundred quid as a refund because that’s what they had calculated as the “value” of the piece that had broken.
It took quite a lot of effort to negotiate them up to a value that would allow me to replace the frame with something equivalent. In the end I had another FS frame from them with a small top-up payment from me. the result was ok but like I said it took some pretty aggressive negotiation to get a new frame that was equivalent (ie: the same travel and not luminous pink) and that I could transfer most of my parts over to.
I guess it would depend on how much you were saving, and what the bike in question was. But a decent warranty is now a factor in my bike choices.