http://www.business-supply.com/oc2/dept.asp?dept%5Fid=2014798&qu=%40all+card +AND+stock+AND+perforated&r1=&so= http://www.officesupply.com/sku.cfm?mode=full&pbid=2014798&productname=Sparc o%20Post%20Cards "Sparco Products" # SPR0097 perforated 3.5 x 5.5 card stock. $7.83 per 501 cards. Orders less than $25 add $3.95 S&H, orders over $25 are free. Anyone use this material?