It looks like a German company will be releasing Mr. Terrific on DVD, under the German title "Immer, wenn er Pillen nahm," on July 17,2009. Rumor has it that the episodes will have an English language option. I imagine that these discs will be PAL, so anyone in the U.S. who obtains the set will either need a PAL player or will have to have the discs transferred to NTSC. I also imagine that the set will contain all 17 episodes, but I'm not really sure at this point. The trailer they've released on the Amazon Germany site is built around the opening credits and contains footage from 2 episodes: the first episode "Matchless" and the last episode "The Sultan Has Five Wives."
Edit: Latest word is that this release will have all 17 aired episodes and an English language option. The release has, however, been delayed for an as yet undisclosed length of time. Will update when possible.