I was a 3.x 3PP addict. I had tons of stuff.
...
But settings, adventures, locations, encounters? I would buy lots of that stuff up.
Back in the early days of 3E during the d20 "3PP bubble", how many good outstanding adventures modules were published?
Looking through old lists of d20 3pp stuff, such as
Third Edition Dungeons & Dragons Archive: d20 System
there were companies that produced tons of pamphlet mini-adventures from 2000 to 2002, such as Alderac and Fantasy Flight. From what I remember of the Alderac and Fantasy Flight stuff I found in the bargain bins years later, many of these mini-adventures didn't look particularly impressive. (I passed on them, despite being 50 cents or a dollar each in the bargain bins).
Other companies produced many D&D style modules until 2002 or 2003, such as Atlas, Avalanche, Fast Forward, Fiery Dragon, MonkeyGod, Necromancer, Troll Lord, etc ... After late-2002 or so, many of these companies exited the d20 adventure modules market and started producing more crunch heavy splatbooks (ie. new classes, races, monsters, prestige classes, settings, etc ...) or simply closed up shop.
There were a few companies which continued producing tons of d20 D&D style adventure modules after 2003, such as Necromancer and Goodman Games. Troll Lord continued with their Gygax authored stuff, and subsequently Castles & Crusades.
Here's an old press release and thread which discussed MonkeyGod exiting the adventure modules business in 2003.
http://www.enworld.org/forum/general-rpg-discussion/65487-monkey-god-no-longer-doing-adventures.html
Here's a post by James who ran Fiery Dragon, explaining why they exited the adventure modules business in 2003.
Adventures Don't Sell...Discussion - Opinions - Website Discussion - The Game Mechanics - Message Board - Yuku
More generally, here's a rant by an insider explaining "why adventures don't sell" (first posted back in 2003).
The Game Mechanics: Opinions
Are things today just 16 months after the release of 4E, really that much different than 16 months after the release of 3E (ie. December 2001), in regards to the quality of adventure modules published by 3PPs?