They are capable of about 3MOA, in my experience. Price is difficult to say as they haven't been imported in over a year. $400 sounds right. Cosmetic parts are interchangable with the same degree of fitting required in any AK. Unique parts are the magazine (use Wiegers from Interordinance), bolt and firing pin (unavailable). You'll need to replace the hammer with the Red Star Arms unit to prevent premature wear on the bolt since the Century hammer is usually poorly fitted to the bolt. You may want to replace the Fire Control Group as the Century one tends towards trigger slap.
They're great guns, very light in recoil and capable of greater accuracy than the standard 7.62X39 AKM. The magazine Century supplies will not work reliably, but the Wieger is a real quality mag, German made, all steel and nicely finished. Also look out for canted front sight bases, fairly simple to fix but irritating when you have it.