Do yourself a favor and knuckle down, save up, and spend your money on an Aimpoint. You wont regret it. You'll just end up down the road doing it anyway.
I've had BSA, Bushnell, and Tasco's on my AK's, with varying results. The Aimpoints cost more, but you do get what you pay for. The biggest advantage is battery life. The M2/ML2's run 24/7 for over a year, the M3/ML3's for over 5 years. I dont even bother to turn mine off anymore. Another advantage is, you can also shoot them with the front cover closed. This was you can set the dot to a comfortable brightness and go from bright to light and back again and never loose the dot. It also eliminates the need for a killflash.
As for mounts, the best by far is the Ultimak. I dont know if you can get one for the Saiga Sporter, but it will fit on a converted Saiga. I have one on both my Saiga conversion and my SAR. A forward mounted red dot mounted on the Ultimak is the only way to go. It sits low enough to shoulder and shoot just like your iron sights and with the right ring, will cowitness with them. The sight sits up front, out of the way of both handling and field of view. You will be amazed at how fast and easy it is to shoot with and make good hits. Snap shots at 100 yards are a breeze. I have yet to see any other set up work as well. The Russian sights sit WAY to high for natural shooting and some of the mounts offset the sight. They also tend to be bigger units that are right in your face and block your field of view.
