I often see players in that 250' mark throwing discs that are too stable for them. The newer high speed drivers (Wraith, Rex, Surge and the like) all requrire a significant amount of velocity and spin to get them up to "cruising speed," which is the speed at which a driver flies straight without banking off to one side or another. To make up for a lack of velocity, some players torque their shoulders over. This creates an unlevel throw (as phisherman mentioned), which can create that wobble, and most importantly, a serious decrease in distance. It's important to keep your disc line and shoulder line parallel. Assuming you throw backhanded right handed, if your right shoulder is level with your left shoulder, then the disc should be thrown on a level plane. If your right shoulder is higher than your left shoulder, the disc should be thrown on a low to high plane. If your right shoulder is lower than your left shoulder, than the disc should be thrown on a high to low plane. Also make sure you aren't rolling your wrist. If your wrist is rotating clockwise when you're throwing, then it's rolling. While this is desirable on some throws, you don't want to have it when your learning to throw.
Until you get that wobble out of your throw, stick with fairway drivers (speed 7 and below on the Innova scale) or midranges. 80% power, 100% technique. You'll be amazed at how far those older school drivers can go. They're very accurate and very forgiving. Something like a dx leopard or dx cheetah would probably serve you well. d cyclone or d XL if you want to go the discraft route.
