Eager to size up Cupertino's latest tablets on the Now Network? Better call your local retailer -- Sprint is now offering the iPad mini and Apple's 4th generation revision at select brick and mortar locations. Existing smartphone customers who make the trek down to their local mini-mall will be able to add the slates to their account at a discounted rate, scoring a 1GB data plan for $15 per month or 100MB for $10. Sprint will also be enacting a waitlist system for customers who miss out du