I paid $160 picked up for my little Spider female from a breeder via Craigslist (a reputable breeder who regularly visits and sells on Fauna). I agree to defiantly take caution with any Craigslist purchase and check over the guy thoroughly.
For the wobble, mine has one that I would say is visibly apparent but not extreme. It adds to her quirky-ness. I can see how some would see it as a little nerve wracking if they're not familiar with it but just know that most if not all spiders have this to a degree (like jjmitchell stated) and as long as he's a good eater it shouldn't be a big deal. Keep in mind though that some spiders do corkscrew, which looks IMO kinda scary but I don't hear of too many spiders doing this.
If you like him and he's healthy and a good eater I'd snag him and not worry about his wobbles (or lack there of) and enjoy the new addition.