There are walkthroughs ( GameFAQs etc ) that list all DKS armor set and weapon locations.
I remember being able to buy some but also having to quest for others...Necklace on marker, boss loot or hard jumping / fighting deals.
Kind of a pain in the butt to have to track down all these different pieces of armor / weapons / jewelry and not knowing what the end result will be...unless you already know.
I'm lvl 25 and still using the Annihlator armor I got with the game from Steam. and I could put it on at level 15.
With a few enchanting adjustments it's still holding up pretty well.
I have all the named armor at the tower...
I just did find the Echelon gauntlets for the first time..so that set is starting to look up. ( New run through )