At that price point you just can't assume you're getting bullet-proof quality, or really any sort of quality assurance other than inspecting the brakes after the shop completes the build. I'd guess you have maybe 3000 miles on the bike. Like I said, I would relace the wheel yourself (since it sounds like you have all the tools needed) for $1 a spoke. Either borrow a tensiometer from someone or learn to do it by pitch, and just keep on rocking until your wheel is really shot. Since you presumably have a relatively true wheel right now, you can get away with replacing them one at a time, making sure you have the lacing pattern right, and then just upping the tension. See if you can bribe the shop into putting spoke prep on your spokes for you, and take it slow and you shouldn't have problems.