The best place for batting I've found is Joann's. In fact, I ordered another roll of Warm and Natural from their site today (90" wide x 40 yards); it's all I use in my quilts and my customers' quilts. They had a 50% coupon code that expired today, which is the reason I deal only with them when it comes to batting. For thread, the best top thread is King Tut, although I have used Essentials from Connecting Threads as well. The best bobbin thread is Bottom Line by Superior. I've also used the Essentials Pro from Connecting Threads in my bobbins, but find that it doesn't go nearly as far as Bottom Line, so I don't really end up saving any money.
Good luck with your new venture!