I had to go to the BBB for one Hitachi rebate ($80!), but they paid. The problem was that Hitachi reused the promotion number months apart and then refused to pay the second rebate due to a "duplicate submission". That seemed like a one time thing. Seagate OTOH seems to be avoiding rebates, or at least making people resubmit, from ANY store.
I've never had any other hard drive rebates from Fry's go unpaid (Maxtor, Seagate, WD, Hitachi) and i've done dozens.