Sponsorship is completely free, unless you like to help a college student out, then it's $1 (it's technically $5, but you get $4 off with a discount code). But if you just want to swap buttons, I'm totally down with that. Just go to my sponsor page and you'll find passionfruit. If we swapped buttons this month and you would like to renew, email me: firstname.lastname@example.org and I'll renew your button on October 1st.
I look forward swapping and sponsoring you next month!
Have a lovely day!