I have never sold any heavy stuff (more for shipping) so I was always able to offer free shipping. I have watched similar items sold, one with free shipping and one with shipping added on and it seems to me that the free shipping ones often go for more money (more than the other one plus the shipping cost).
As well as 50 free items/month, eBay often has free listing on Tuesdays. At least they did when I was active a year ago. This is a great saving if your starting bid is over 99 cents.