Be sure to add Greg Holland's superb VALIANTComics.com to your list of bookmarks. Even if you are not a big Valiant fan, you may be after spending some time at his site!
To me, Valiant is a double edged-sword -- they represented the best and worst of comic book collecting. At their height in the early 90s, Valiant produced great comics with engaging stories and solid artwork that awakened the excitement that we remember as young comic collectors who couldn't wait for the next issue.
Sadly, when the honeymoon was over circa 1995, things got ugly fast. Valiant released some of the most unreadable tripe ever printed. Recently I picked up a complete run of Ninjak and thought it would be fun to read it beginning to end. Let's just say I didn't get any further than issue #2. Too bad they aren't worth more because they would be perfect slabbing candidates -- gorgeous covers with horrible contents. Thankfully, I didn't pay more than 50 cents an issue for the Ninjak run.
For some good Valiant reading, check out the early issues of X-O ManoWar, Solar, Harbinger, Eternal Warrior and Magnus. While super high grade slabbed copies may cost a few bucks, reading copies can be had cheaply and most early runs were reprinted in trade paperbacks.