Interesting. Last I heard, David had given up on updating the VLDB back around 2004 or 2005, and it was always a free download from his website. Now, if he decided to make a buck or two off the updated version, more power to him! But if this is someone posing as David to make a buck..... I have no knowledge either way, it just caught me by surprise to see RenderMan's link.
Back to coder's quest... a number of years ago I wrote an article for a now defunct website on how to get started with ObjectDBX. I'll see if I can find the original and post it here (perhaps I already did so a long time ago, I surely can't recall though).