I buy Heat and bond lite by the bolt at Jo Anns. Using a coupon or waiting when they have interfacing for 50 percent off. At mine its behind the cutting counter , Ihave asked and ordered a whole bolt when the in - store supply is low. I can still use the coupon or get the sale price. The manufacture stopped producing the heavy on the bolt a few years ago.
I too prefer the heat and bond lite as it does not separate from the backing over time like wonder under.