Well that's interesting friend of mine just got it back from RMA for the exact fan failure. I don't know anything about fan repair. But i can tell you if you gonna replace them it will be expencive. 20$ for one or a pack for 40-60$. He even started to look at arctic cooling to buy a whole new custom cooler. If you don't want to throw money and don't care for looks you can zip tie a 80-120mm fan and plug it into mobo or molex.
I think on the strix either all fans or none of them will shut off.
A glance around eBay has a replacement set of 3 fans at ~$60, so that is probably the cheapest option if you can't get it RMA'd. You could do a kraken g10 setup, but that would be much more expensive and the VRM would probably run hot on a card that powerful.
You're right that the 7k series typically run cheaper, but they usually aren't that bad on the newer models. might be inflated right now because that's the first thing to go on mining cards, and mining is a thing again (rip reasonable market prices)