You are in luck...well sort of. There is a Gravely dealer that is in Wisconsin and is stocked full of used Gravely parts. They have tractors stacked up like cord wood. Every conceivable attachment. Unfortinatly, they know what the stuff sold for and are very expensive. They also don't like to sell used, instead prefering reconditioned. This kicks the price up even more. At least twice of anything that you'll see on ebay. The dealer is called Frank Gast and son (Frank died years ago and the son is now pretty long in tooth) and they are in Caledonia, Wisconsin. Give them a call. He loves to talk about Gravely's.
Ultimatly, keep watching ebay. Sooner or later a mower will come up that is local. Having used one of these 30" mowers I can attest to their effectivness. If you have one of the older tractors with the original Gravely engine, then the ballance will be ok. The later Kohler equiped models had the center of gravity just a little too far back. Trust me in that you can hurt your self pretty badly when the mower kicks up. Also be sure to get the chain guard. It really increases the safety of the mower. I can also attest that this mower does a excellent job with mowing seedlings so be careful. If you are looing to cut only a couple of times a year, the sickle mower may work better. The field doesn't look as nice, but the mower is wider and allows a greater ground speed when cutting the thick stuff.