The donate link will be:

https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=X3FRBC4X6E88N&lc=US&item_name=Pebble%20Cards%20Development&currency_code=USD&bn=PP%2dDonationsBF%3abtn_donateCC_LG%2egif%3aNonHosted

It's a PayPal link.