I e-mailed A&E about this on Friday, and I got a response back today. Here is is:
Hello from A&E Television Network and thank you for your message. The Space: 1999 DVD mega set with bonus disc was an exclusive for Best Buy customers. We are however anticipating the release of a bonus disc to be released in January 2003. This bonus disc will be sold seperately.
Please let me know if you need additional assistance.
So this looks like a good sign, except that we have to wait until January...
I just answered my own question - & ordered the bonus disc directly from A&E's store. I called their customer service dept. to ask if there was any news on this, & I was told that the disc was available for purchase.
Good thing I didn't eBay my prior sets...
Just wanted to note much to my pleasant surprise I just ordered the MegaSet from overstock.com (last one in stock at the time.) And included was the bonus disc! Now I'm not sure how overstock gets their inventory...but the assumed fact that only Best Buy sets had the bonus disc may not be 100% correct at this time.