What a beautiful quilt! and yes...such a bargain. I've made a few now, and wanted to share the best tip I received after struggling with the stretchy t-shirt fabric on the first one.
Use a lightweight fusiable interfacing on each of the t'shirts, iron it on before you cut the blocks... you'll be AMAZED at how pretty and square the blocks then stay for you to sew. It also makes them much friendlier when you start quilting, the needle seems to go through the designs much smoother, etc.
Again - LOVE the harley quilt - beautiful colors!!