MrMaxheadroom

I would say wait till you can afford a card that lasts you 4+ years (personally I don't tend to upgrade, but rebuild from scratch every 5 years or so) but if your current card is failing you might be better off shopping around for a decent stop-gap bargain I've found this chart very helpful in the past http://www.tomshardware.com/reviews/gpu-hierarchy,4388.html So long as the card you're looking at getting is at least 3 tiers higher than the one you currently have you should see some decent improvement. So use that to narrow your search then go looking for specific reviews for the benchmark scores

My rule of thumb (not necessarily just for Maxwell-Pascal) is its better to buy the pinnacle of the last generation tech (in this case the 980ti) over v0.1 of the new generation So in this case id say get a 980ti and then a couple of years or so down the road after Pascal has had a few revisions and a TI update go for an upgrade then. For the record im in the same boat and about to do a new build which will probably have a 980ti (but my current pc (which has served me well) is like 5 years old now with a Radion 4960)

Don't forget we pay 20% Value Added Tax (VAT) on everything here in the UK, so if you really want to guesstimate the price in $ start from the ex-vat price, ie £800 Which at the current exchange rate is $1645 Canadian