Unless you are LE the best price out there is through GSSF. It costs $35 to join and $25 to renew your yearly membership. Being a member of GSSF allows you to shoot in the Glock shoots where you can win different prizes including Glock pistols, gives you access to the Glock armorers course, and lastly the ability to purchase Glock pistols at a reduced rate that is under dealer cost.
Here is the link to the prices.
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Here is the link to the GSSF page.
http://www.gssfonline.com/
