Yup unfortunately this is the exact situation I find myself in.
My ancient HD 4850 (yep seriously) has finally given up, to be fair it was the oldest component still in my machine.
I've tried and failed to get anything half acceptable to replace it from new. My expectations are not particularly high, I'm looking for something performance-wise above say a GTX 1060 / 690 ish, 6GB+, and sub-£300. I ummed and erred a few seconds too long and missed out on a RX 580 for £240 from a competitor, but I'd really prefer nvidia anyway as I seem to regret it every time I get a radeon.
Case in point, I was desperate and ending up paying £160 for a used R9 390X from fleabay, arrived yesterday and I reckon I've had more blue screens in the last 24 hours than in the previous 30 years combined.
What are people in this position doing?