I have the Hi-Point 9mm carbine, an SKS, and a 7.62 Saiga. You wouldn't go wrong with any of them. I think I heard where you can now get 15 rd magazines for the Hi-Point. Modifications can be made on the Saiga to use AK 30 rd. magazines, or as I did, just put a dome head screw in the front which acts as a ramp and the round is chambered quickly and easily. I spent maybe a dime.
From what I've heard, and I don't have any firsthand knowledge of this, is you can forget about reliability of the 30 rd. SKS magazines. Some may have actually worked, but the other 99% haven't. Might work for plinking, but the 10 rd. fixed magazine is adequate for home defense and the stripper clips do load quickly and easily.
For home defense, I'd go for the lighter and shorter Hi-Point. The Saiga is slightly longer, the SKS is too long and heavy if you need to swing it around to aim. Of course, the bayonet might prove useful!
For general plinking, the SKS is cheapest and has excellent iron sights. For all-around usefulness, the Saiga pulls ahead in this tight three-horse race.
Of course, those were the only three horses I put in this race. The are other options, of course, but probably none cheaper. I have an order in for another Saiga. I hope they are imported again soon.