I just got finished buying a CSA VZ 58. After all the looking around, reading and research I learned the CSA VZ is a new production rifle that is NOT military surplus. The finishing on it is excellent. On par with any high end rifle. This quality finishing may only be for appearance as they both have great reviews functionally speaking. But the CZ 858 is a true military surplus rifle built to work great, not look great. Of the close up pics I've seen of both I would strongly agree with these findings. The 858 looks rough. Quite ugly IMO. So, at the end of the day, your partially paying for the looks and finish quality. BUT... my buying decision included the next point as well.
I don't like the fixed wood or metal folding stock and I don't like the wood furniture at all. So, if I bought an 858 id end up buying the M4 style tactical parts anyway. Which would cost a minimum of $150. So, once I buy the cheaper 858, install the parts I want I'm up to $850 or so (give or take). I bought my VZ 58 for about $885 plus tax from Frontier. For the extra $35 I got the nice looking, high quality finish of the 58 and I don't have to do any of the work.
Ive also read the VZ includes a side optics mount plate. But I havent confirmed this yet. On the other hand, the 858's pretty much all come with 4 mags whereas the VZ 58 only comes with 2. So thats a consideration cost wise as well.