I combine shipping for auctions paid for and shipped at the same time and with the same shipping method. 

For media mail items (books, comics, manga), the combined shipping is the highest shipping cost for the first item and then $1 per book thereafter.  For non media items (or shipments with a mix of media and non media mail items) it is the highest shipping cost for the first item and then 50% of the shipping fees for each listing won after that. Media mail items are shipped via media mail. 

I expect payment within 3 days of the auction closing and will ship within 3 business days of payment.  Please contact me with any questions and happy bidding!