Obsidian is one of those items that increase in value the more of it you have. It's easy to find in a small quantity but if you want lots, for example to build a bunch of portals or a large building, it's a pain and you'll have to go around to lots of different shops. At the DC level there is one in auction > 60k. But individually they usually range around 10-14r.
This 1r start, no bump auction can serve as a price-check of sorts. However, no-bump auctions usually end up cheaper than market, but you never know. This is my auction that is going on now. Thanks. http://empireminecraft.com/threads/auction-dc-of-obsidian-1r-start-no-bump.45071/
