Yeah, when I bought mine it was like 100k but that was a long time ago and then I bought one a few months back for 50k. I guess it just depends on how much a person is willing to pay and how many are being offered at the time.
I personally bought my current Netherhound egg for 70k. However, they have risen in price dramatically since then from my knowledge. I suppose this is due to the fact that over time Netherhounds can be lost, whether through item frame glitches, entity mishaps, or a simple misplacement. So I predict the price is around 100k-150k now, and will only rise as time goes on.
They were only 500r back when you could egg them. It took a full year (and probably more) to get to 50k-60k.