Have been using BunnyCDN for about a month now and noticed their credit coupons stack ($5 credit per coupon).
Their pricing and service is very good, with only $1/mo minimum spend.
I've been running 6 small business websites on it over the last month and didn't go over the $1, therefore this $15 credit should last me the next 15 months of use.
They also have a 14 day trial which is used before using the credit.
Would highly recommend this for anyone running a website.