I've been keeping my eyes peeled on eBay for a good deal on a used cylinder head. They are rare as hens teeth, and expensive when they do pop up. On eBay, I saw a new OEM bare head assembly (i.e no valves, valve springs or cams included) be listed "buy it now" for $800+ By the time you've added replacement cams (you'll probably only need a new exhaust cam) and all the valve train parts you're talking well over $1K! Almost better off looking for a parts bike for yourself. Used KLR650 engines go for $1500 to $1800 on eBay - maybe you can get lucky and find a complete parts bike and/or a good engine relatively close to you for roughly that price, or less? Trouble is, everybody is looking for good deals like that... I know I am.