How to publish magazines (in PDF format) to Apple Newsstand?
If you do not have a dev kit you can use other companies who build, release and manage subscriptions.

One such comapny is Woodwing 

However these options are generally very expensive. You are better off (if you can create and develop the product yourself) purchasing the SDK license ($99 per year) or failing that you can use Adobe software to publish the Newsstand Magazine but that costs about $500

There is more information on Newsstand here