Its not that hard to do, basically a bullet guide will have to be installed in front of the chamber. It requires the part and drilling and tapping the trunion, not a big deal if you have ever tapped a hole before, or can have someone do it. A lot of people make their own bullet guides from pipe, or I even made mine of flat strap bent and ground to shape.
You can set it up basically 2 ways. 1 is to file the mags down in the rear latch to fit the latch on the rifle. This way you can still use the factory magazine and some others that will latch in without surgery. Or you can file down the bump under the mag latch so it takes most standard highcap AK mags. Either way you sometimes have to file mags in front of the feedlips to relieve enough material so it will seat in the receiver. This is minor stuff to get them to fit, its the feedramp that is more important to how it will run.
The other thing with the factory Saiga is some can't deal with the trigger. I have polished them up to improve the feel and learned to get used to it. But after converting a couple, the fire control groups made in the US are a lot better.
If you didn't want to screw with mag conversion etc, a WASR or something used may be cheaper, though probably not better.