For 8" valves my guesstimate would be about $10K per valve or about $2M for 200 of that size.
Please remember, I don't know what size valve they are making right now. Could be 4" or 8" or anything else. On their website HiAlloy says they can manufacture valves of the following sizes:
3-Piece Body Trunnion Mounted Ball Valve
Hi-Alloy Valve's ball valves are trunnion mounted supported and available in sizes 2" to 48", ANSI class rating 150 to 900 lb. .... HAV's Ball Valve Trunnion Mounted supported and available in sizes 1/2" to 48", ANSI class rating 150 to 2500 lb.