Kind of depends on how desparate the buyer is for one. I've seen them go for a couple hundred k (usually 300k range is low end) and I've seen them go gor 750-800k (high end)
Bonus points since you're on BH you can probably put a 500k+ price tag on it (depending on how many are for sale on AH and for how much.)
SL is around the corner though, will probably make the ring not that great, don't think anybody would blame you if you tried to sell it for a lower price just to get a quick buck while you can.