Yes, I agree with HD. "L" doesn't necessarily fix anything. The "L" 70-300 has the same variable aperture as the non-L, it's just sharper and focuses faster. And for that it costs $1600, instead of $650. Being an "L" didn't solve your problem, just lightened your wallet.
However, there are options, depending on your needs. At 200mm, the 70-300mm is f/5.0 (see chart here for many lenses:
http://www.the-digital-picture.com/R...ns-Review.aspx ). If all you need is 200mm, the 200mm f/2.8L can get you f/2.8 (1 2/3 stops faster than f/5) for just $800. Much better than the $3000/stop prices HD mentions at 300mm. And it's super sharp to boot. You can even throw on an extender and get a 280 f/4 lens, mimicking the long range of your 70-300 (though much slower at switching between 200 and 280mm than your zoom lens!)