I also have the shipping issue so here was my strategy for both my deals (and I did make a few hundred dollars off of both of them). I went with a lower priced/value deal and based it on the lowest cost of my items, which is pretty much $14 plus $8.50 shipping. What I did was to offer $16 in credit for $7. It's not as much money upfront obviously, but I knew that since at worst, every order would total $22.50 so everyone would need to be invoiced for $6.50. This was how I ensured the shipping costs would be covered. That said I didn't make any money if a customer only ordered 2 dozen cookies.
In my first deal, when I was clueless, I found that many people ordered a 3 dozen cookie sampler that they could customize with their cookie selections. The cost of this product then was $20 (I later raised the price after I realized it was inconsistent with other products in my store) plus $10 shipping. The other product I had that sold very well was a box of cookies with free shipping. This item the customer doesn't get to specify what cookies they want, it's basically a surprise and I put in whatever was baked fresh that day (i.e. overage from other orders). The cost of this is $28 with no shipping cost. It was these items that allowed my deals to be profitable. And I would say that well over half of the Heartsy customers ordered these items or purchases multiple items.
I guess my point is that you need to try to craft a deal amount that you can be assured that you will be able to come out ahead. It is absolutely critical to run the numbers. I tried various amounts/ scenarios before I settled on the deal I did and I was very steadfast about it in my negotiations with Heartsy. They of course suggested something crazy. When I went back with my counter and explained why I was offering the amount I was, they were fine with it.
