Oh, and if you're going to get a lens, I think most people starting out are absolute perfect with the el cheapo 70-300 mm lenses. Most people don't need any better, and if you actually think your photos look blurry using this cheap telephoto lens, it's probably your lack of tripod. You're gonna get some not-so-sharp photos if you shoot at 300 mm focal length by simply holding the camera in your hand. Lots will probably end up blurry.
However, if you really do plan on shooting lots and lots of sports, or you want to start working on bird photography, then yes, spend money on expensive lenses that reach to 200, 300, 400, or even 500 mm with a decent f/4 or possibly f/2.8 aperture size, because you'll need to.
If you're going to spend money, do so on a wideangle lense, like a 14 or 15mm prime, or one of those 12-24 mm, or 10-22 mm lenses. That's where money should go, not on a zoom that goes beyond 300 mm.
Oh, getting a macro lense (ie: the lenses capable of focusing on a subject only 10-20 cm away from you) might also suck up some money.
So if you're starting out, it's probably a good idea to get:
1) A wideangle lens
2) A "prime" lense like a 35 mm or 50 mm f/1.8 or whatever, since primes are generally very sharp and have massive apertures for a low price, which makes it great for taking photos in dark situations without flash, like inside some restaurants.