Israel without spears and the value of a shekel

It is stated in 1 Samuel 13:19-22 that Saul's army didn't have any swords or spears, due to the Philistines "not allowing" Israeli blacksmiths. > Now there was no blacksmith to be found throughout all the land > of Israel, for the Philistines said, “Lest the Hebrews make themselves > swords or spears.” But every one of the Israelites went down to > the Philistines to sharpen his plowshare, his mattock, his axe, or his > sickle, and the charge was two-thirds of a shekel for the > plowshares and for the mattocks, and a third of a shekel for > sharpening the axes and for setting the goads. So on the day of > the battle there was neither sword nor spear found in the hand of any > of the people with Saul and Jonathan, but Saul and Jonathan his son > had them. (ESV) How did the Philistines achieve this? I assume this has to do with cost - what is the modern day equivalent of 2/3 or 1/3 of a shekel? Is there some other reason that Israel didn't arm themselves - or did they use mainly non-metal weapons?