This of course assumes that one wants to convert it to be exactly like an Arsenal. If I were building a function driven fighting gun I certainly would not. A base saiga is $300. $400 gives a lot of room to add some good functional enhancements. Rather than pay 700 for an arsenal I would build something like the following.
Saiga: $300
G2: $25
retainer plate: $5
Pistol grip: There are a lot of options that are much better than the Popsicle stick grip that comes with the Arsenal. $20
PG nut $5
Stock: the two setups I prefer are either a Vltor tube and a magpul stock (about $120) or an internal block, folding mechanism and a magpull stock ($40, 70, 15, 5, 40 respectively) for about $170
Thread and add a flash hider: prices vary but a A2 style birdcage it maybe $10 and vortex is $70 both are much better on a fighting gun than the 74 style brake IMHO. Local prices may very but around here you can get a barrel threaded for 50. Also lots of people like to mover the sight back, cut the barrel, and pin a muzzle device improving the balance, handling and size of the gun. That might cost a bit more but not much.
There are a whole bunch of options for mounting optics, lights, etc. I think the best choice really depends on exactly what one wants to do with the gun and certain personnel preferences. If I were going to run an ACOG I'd get a TWS top cover rail. Other viable choices depending on intend use run from just using an ultimak gas tube, to the various MI hand guards and top rails, to the new TWS hand guards. There are option form about $90 up to $260 that add serious functional enhancement to an AK.
Depending on the exact options one can come out right around $700 and have a gun that is much more functional than an arsenal built to give you a particular look.
