I have heard of at least one Bonneville out there with at least 155,000 miles on it so I personally am not concerned with the head wearing out. That being said, there are complete low mile motors out there starting at around $1k. As was previously mentioned there are also plenty of low mile bikes out there for low money, heck I just saw a 2003 Speedy with 6700 miles on it going for $2800 a few hours away from me. What I would not recommend us doing is holding our breath and hoping for an 1100cc America/Speedmaster. If the rumor of an 865cc water cooled motor to replace the current one on an entry level holds true, I have a gut feeling that the America/Speedmasters will get saddled with that engine and not the 1100cc. That way Triumph can push those wanting a bigger cruiser engine to the Thunderbird models.
2006 865 Neon Blue/Jet Black Speedmaster,790cams, TTP Stage 2 Firestarter, Epco Exhaust with 10.25" Samson Vrod baffles, UNI pods with 40 pilots, 150 mains,Thruxton needles, 3 turns out.