Seemed clear to me the first time. Not sure how you could interpret it to be $8 for 1 or 4 issues (I get to pick? Well, I'll go for all 4!), but $25 shipping for each (I better expect it sitting on the doorstep when I wake up tomorrow morning).
I suppose you could have worded it:
The "plus shipping" is awful repetitive, but when you're trying to be informational, it's ok. Or, I'm obviously not afraid of parentheticals, so you could throw it in that way with (plus shipping) or even (+sh). But, really I'm not sure even how it could be confusing unless people think you are just trying to drum up business for FedEx at your own expense.
Best of luck with the new endeavor. Now that you get to wear the publisher hat, as you can see here, the fun ride begins!