A patch enables you to change ammo price of both primary weapon and secondary weapon.
You may need to update the game to the latest version (Alpha v1.2 + Patch #1) to use this patch.
=Patch=
Copy patch\cstrike folder into game's root and overwrite files.
=Restore/Unpatch=
Copy restore\cstrike folder into game's root and overwrite files. Then, delete [gameroot]\cstrike\hscustomcvar.cfg.
=Edit=
By default, the ammo prices are the same as the original game, and you can go to edit [gameroot]\cstrike\hscustomcvar.cfg to change the value after "hs_ammo_price_pri" and "hs_ammo_price_sec" as you like. Another method is using game console(press ~ key) after enter a map and type in these cvar and value for the effects.
*Ammo prices on addon menu still shows the original 350 and 300 for primary and secondary respectively. This is because I didn't add sprites for them.