It all depends on the rings properties. It also takes 10 Ecrus to make one ring (I have seen these go for 350K per 10) and even at 100 tinkering with a good talisman, I only seem to get the 50% EP mod on about 6 out of 10 rings.
a ring that had 2 dex and 50% EP, might go for 250k to 400k, depending on the buyer and seller. Something like 1fc, 2fcr, 50% EP, 7 taming, and 8% hit chance, (best one I have) would be worth millions.