Oh duh! Right, there is nothing illegal to buy.
"manufactures or causes to be manufactured, imports into the state, keeps for sale, or offers or exposes for sale, or who gives, or lends, any large-capacity magazine."
On another note, so if someone (maybe an armored car owner) says that he'll have 200 high cap magazines sitting around a place, people can go pick them up?
Sure it does.
Armored Car Company (ACC) purchases and/or imports a large cap mag. <-- legal exemption from PC 12020
ACC offers for sale a large cap mag <-- legal exemption under PC 12020
Joe the Plumber takes the ACC up on its offer to sell - aka offers to buy the mag. Legal, there is no prohibition on Joe for purchasing mags.
Correspondingly ACC sells to Joe <-- legal exemption under PC 12020
Joe now posesses a newly purchased mag. Legal, there is no prohibition for posession of the mag.