Sweet Maria is a great source for green beans. They specialize in home roasting and have a full line of coffee roasting and brewing paraphernalia.
I started roasting with an I roast years ago. I could never dial in the roast I wanted. The beans would burn fast you have to watch those machines like a hawk when you roast and I also found out those machines aren't made to last more than a few years. Behmor makes a roaster which is pricier than what you have but is still reasonable and it does a way better job unless you like really dark roasts.
Often times local guys will sell you green beans for almost the same price as roasted and that's a rip off. Typical green beans should be in the $6-$7 a pound area. Of course some can go way higher and robusto beans they practically give away.