Alright, it looks like even the biggest order will fit into a medium flat rate box. The flat rate box price is $12.35 online and I expect to pay ~$5 for packing tape (~$1 a person) since I can't ever seem to find it cheap, at least not for decent tape. So I'll be invoicing everyone for $15 to cover those costs, a little for gas, Paypal costs, and a little extra to defray any additional shipping materials I may have to purchase.
If you'd rather I ship by weight, I can see if I can scrounge any boxes and let you know what shipping will be.
Edit: Cost Breakdown - $12.35 flat rate shipping + $0.85 tape+ ~$0.75 PP fees + $0.50 gas + $0.55 any additional materials cost. If I can get shipping cheaper and have no additional costs, there will be a small refund.
Again, if you have any questions, need to change anything, want to combine anything, and so on, contact me ASAP so I can work it out.