It's simple. 

Spend $150 in this store (cumulative over multiple orders).

Get a gift certificate for $15, redeemable within 60 days. 

Please note that it will take 2 weeks for a gift certificate to arrive in your email inbox (sorry, but I need a smidge of protection against cancellations), and they are not redeemable for cash.  If you need to receive yours earlier, please contact me.  Happy yarn shopping!