Cheaper, yes.

 Comparable efficiency AND comparable hashrate AND cheaper, no.

 When the current "mining shortage" price gouging dies out, the RX series will return to being a little less expensive on hash/$ (but will lose a little on hash/watt).

 Or go with the already mentioned Tahiti-based options if you can find a Tahiti-based card cheap enough.


 7950/7870/R9 280/R9 280x are all based on the same Tahiti GPU, the 7850 and R9 280 had a few of the cores disabled usually due to a manufacturing flaw in the chip though on occasion they had a few cores disabled in the BIOS because AMD didn't have enough "flawed" chips and had to use "good" ones.