Outside of eBay or buying from used video stores, you really only have three avenues.
On one hand, you can buy the recently released "Singles" from the Japanese Dragon Box. Unfortunately, these discs are Japanese only, and have absolutely no subtitles.
What you'll probably find more suitable to your needs, however, are the official Madman Entertainment releases from Australia. These sets are exactly the same as the English releases, except you can actually get the "Uncut" version of the first 13 episodes, while, in the US, you can only get a heavily edited version of those episodes. They also have two boxsets that collect all the individual volumes.
Boxset One:
http://www.madman.com.au/actions/catalogue.do?releaseId=7138&method=view
Boxset Two:
http://www.madman.com.au/actions/catalogue.do?releaseId=7139&method=view
Unfortunately, these are PAL and Region 4, so make sure you can actually play these discs before you hypothetically order them.
And, finally, one could assume that FUNimation will eventually release the series in their current boxsets. Unfortunately, these could be cropped in widescreen like the current DBZ sets (though, it's looking as though the "Remastered" GT boxsets will be left in the original aspect ratio). You could just wait for those, though, that may never happen.
So, yeah... I hope I was able to help you in someway.
The Tournament Saga will sometimes go for $200+
