For $700-$900 there are tons of awesome guns. What I would get is probably different than what you would get since it depends on what you already have, and of course what you want to do with it.
That said, you might to check out the HK VP9. I really love mine. It's pretty "cheap" for an HK, too. I paid $599 for the gun with Meprolight night sights and two mags (you will probably pay more but not a lot more). It uses P30 mags, too. Great shooting gun! It's fun to shoot, accurate and very adjustable; it has three interchangeable grip panels with 3 different size panels for each for a total of 9 grip pieces (total of 27 possible combos).
It's about as big as you would ever CCW but it's doable. It's an awesome range gun, would be a good home defense gun and it's easy to shoot well. For the price you have money left for ammo or to apply towards reloading gear.