|An effective choice for a century|
Raise the budget to $300 and you can find a used .38 revolver from Taurus or a well-used Smith and Wesson or Ruger. Right now you can find surplus CZ-82's for $250 and they are well-made firearms. This is about as cheap as you can expect to find a quality handgun. You can find Hi-Point carbines in this price range, these are getting a reputation for being reliable and are chambered in common pistol rounds, like 9mm and 45acp. If you are lucky you can find a used SKS rifle in this price range as well. You can often find used lever action rifles for less than $300 as well either in the very common 30-30 or pistol calibers like 357 or 44 magnum. A used Kel-Tec Sub-2000 is another pistol caliber carbine that can be a good choice.
|The Saiga series of rifles are a bargain|
|The AR-15. You totally need one.|
These are just some ideas. Lots of people buy their first gun and find out it's ill suited to their purpose or desires. Ask a lot of questions before you choose. If there is a range that rents guns try out a few before you decide. Go to different shops and see what they keep in stock. Keep in mind that in most of the country we pay 70-80% of MSRP, so don't be scared off by prices on manufacturer websites. Take a class and listen to the instructor's recommendations. Go shooting with friends. Ring me up if you're in my neighborhood, I love taking people to the range.
I've been pushing rifles and shotguns here, but if you desire a single gun that you want to fill multiple roles that could point you at a handgun. If you desire a gun that you can carry concealed and use for home protection than a handgun is the best choice. But if you want a firearm that's dedicated for home defense a rifle or shotgun will likely serve you better.
As always if you think I've missed some obvious choices or have any questions or suggestions please let me know.