A lot of my best stuff has been bought from vendors. It really just depends on your luck. If you are finding lots of great stuff that is useful to your character then no need to spend money, but I haven't been so lucky.
I'll say it again, and I can't say it enough: I want to have sex with this game. -JimiMorrison187
The vendor's have fixed lists of uncommon loot, so they're a good place to go to fill in the missing parts. Like if you want a good set of chakrams but you've had horrible luck with the loot, go to a store and buy their best set.
~ PSN ID: ValorPhoenix ~ Raven [ / . \ ] Hubris ~ Bone Ravens "There are more defective users than defective systems."
If you find multi-slotted armor with decent stats from a vendor, jump on it. With the right gems, those pieces can hold you over for quite awhile. It's what I did with my character's Trollhide Armor from Helmgard Keep.
*BEEP* This call has never taken place, I will travel back through time to before you called and STOP you from CALLING!