This weekend only players with active accounts in good standing in EverQuest, EverQuest II and Free Realms receive double Station Cash when redeeming retail Station Cash Cards. 

Only cards redeemed between Friday, September 18th (after 7:00am PDT) and Sunday, September 20th (before 10:00pm PDT) will receive the double Station Cash value bonus.  Cards may be purchased any time in advance, but to receive the promotional Station Cash bonus cards must be redeemed successfully during the promotional period.  Once successfully redeemed your Wallet Balance will reflect your new pre-paid Station Cash balance plus your bonus 100% Station Cash value. This offer does not include Station Cash that is obtained from Free Realms starter card packs.

If you're looking for Station Cash Cards locally, note that they're branded for Free Realms, but will work on all SOE Station Cash enabled games.  For a list of retailers and other details, see Kiara's post on the EQII Forums.