Think Sling Media is partially making up for its ridiculous arbitrary lockout of iPhones on older Slingboxes by offering a $50 credit toward the purchase of a new model? Think again: turns out that the credit is applied against prices in Sling's own online store, which are already jacked beyond reason. Actually, they aren't, they're just MSRP -- but let's be honest, no one pays MSRP for anything anymore, and you can get either the SOLO or the PRO-HD for less from Amazon than from Sling's store after the frickin