What Should You Send to Beta Readers?

Cookies and beer would be a good place to start, but you probably wouldn’t be able to get the media mail rate on that.  Here’s what I did. 

On February 1st, I mailed five packages to the brave souls who had previously agreed to beta read The End of the Iron Age, Book 2. I wanted to make their life easier, so in addition to a spiral-bound version of Book 2, I also included

Instructions on the kind of feedback I was looking for
A synopsis of Book 1 
A red ink pen (aka the red pen of doom)
1 prepaid media mail sticker.
Pre-printed return labels
Two copies of Book 1

Including two-way shipping, the total cost for each beta reader pack was just under $23. Not bad.