To me defensive firearms are like brakes or tires on your car...it's not something you want to save a few bucks on!
That said, there are better options out there. I don't think a Hi-Point carbine is not the optimal choice for home/self defense. Personally, I think a shotgun is better, I prefer a pistol-grip Mossberg Persuader loaded with 3" 00-buckshot Magnum shells. Unfortunately, they're not the easiest thing to store, so I keep a pistol bedside just in case I can't get to my shotgun quickly. My recommendation for a pistol would be something from the Springfield XD/XDm line. As many of you know, I like the .45 ACP but a 9mm works as well. There is no caliber better than another, they just have advantages/disadvantages and it ends up being a personal preference. I would steer clear of oddball calibers like .45 GAP or 10mm simply because good defensive ammo is tough to find and expensive.
The best thing would be to buddy up with someone who would be willing to take you to the range and let you shoot a couple of their pistols. Be aware that shotguns, especially 12 gauge or bigger, are not gentle weapons but they do get the job done, and done well!
Cheers! M2