I would contact Shelia Lee on this net. She has published a lot of free and some for sale material on how to play the accordion. She lives in Galveston, but she teaches some of my children every Friday night using ooVoo (a free internet video servie) You would need a computer with a webcam and microphone.
On the straps go to the National Accordion Association web site and look up the 2011 convention that was held last weekend. Look for the vendors. You should be able to find someone there that sell them. I believe a guy by the name of ED who has a music store in Ft. Worth has them.