Nothing cheap enough that'll make it worthwhile.
Most of the aftermarket coolers are designed around reference PCBs unless stated otherwise, so that's one route...
Any donor card will likely have to be from the 10xx series for compatibility anyway, meaning you're probably looking at conservatively +$100, minimum, on top of everything else you're spending thus far.
Being logical about it... The going rate for a used 1070 Hybrid is around ~$200, maybe $250 at a stretch.
+$50 puts you in $250-$300 territory and +$100 for a donor card/cooler puts you at $350-$400.
With ~$350 and currently sitting with a 1070, I suspect you'd be the target demographic for the (rumoured) mid-tier RTX 3000 series of cards. Rumours suggest they're going to be announced in response to AMDs "Big Navi" announcement/launch.
Given 3070 >2080TI (not by a lot it appears, but still) and 2080TI > 1080TI by ~30%, I suspect you'll see >1080TI performance, new, with warranty, for the same kind of net spend pricepoint (3060/3060TI etc)