I'm not one for felted handles because the wool makes me itch on my shoulder (I swear I can feel it though my clothes!). For my first booga bag, I bought some leather cording and sort of braided it together to make long straps. I got it at Hobby Lobby and I want to say it was $7.99 for the whole roll of it and I got it for 40% off when their leather goods were on sale, which is often!
I'm working on another different felted bag now and lucked into a very cool long wide embroidered suede belt at the thrift store for $2! I've also picked up a couple purses for $1.49 each and plan on relieving them of their handles so I can use them for a felted bag :mrgreen: You might take a look at some goodwill and thrift shops in your area and get lucky too! Hope that helps!