Yeah, most vendors have 1k or less. REALLY frustrating when I've just gathered a ton of items.
I'll usually wait until I need to buy a bunch of stuff from that vendor and then sell back other stuff.
Otherwise, I end up stashing a lot and disenchanting items.
Being a werewolf is pretty awesome. i haven't seen a downside other than no sleep bonus and you can only change once a day. I used it a lot early on but not as often now.
I haven't done much on the main quest either. Keep getting sidetracked with other fun quests. Done a few of the daedric lords quest. Kinda cool they worked those in. Gets you some nifty items too.