Well, kits are good if you have a certain style in mind but no recipe. But if you have a recipe, then you can buy your ingredients separately. I like Austinhomebrew.com, northernbrewer.com, morebeer.com, and midwestbrewing. I've ordered mostly from austinhomebrew.com because I can order ingredients in whatever increments I want- at some of the others, if I need an ounce of black patent, I have to order a whole pound. They also have a flat rate shipping, so it's not such a big expense for shipping.
Look over our recipe database, and see if anything looks good. Otherwise, those online homebrew stores have great kits like clone recipes of your favorite beers. That's what I used to do- find a beer I liked and buy a clone kit.