Check this out (top reasons why shoppers abandon carts):
#1 High shipping charges. 44%
I offer "free shipping" on most item in my store because of this factor.
Buyers often have an idea on what they *think* it should cost to ship something. 99% of the time they're wrong in the shipping estimate in their head and it actually costs more. If they see you're charging even just $2 or $3 more than what they think it should cost it can kill the sale. Now they think you're trying to rip them off in shipping charges. The weird thing is it's often the shipping charges that will seal the deal in making the sale rather than the retail price.
They have no idea how much your handmade item should retail because the prices range in handmade so much across the board. They think they know what the shipping should cost and people are so freaked out and conditioned to watch out for jacked up shipping costs.
I totally get rid of the chance buyers will abandon their cart due to high shipping charges because I have no separate shipping presented to them.
Marketing with free shipping has worked really well for me. I do get feedback that says something like "Can't beat free shipping! Thanks!" or something about the free shipping.
You never know unless you try it to see if it works for you. And when I say try it I mean for like 6 months straight or a year rather than just 1 weekend.