"Anybody know where I can purchase a 45 Cal Hawken at a reasonable price?"
Get a beater in 50. Buy a Green Mountian barrel blank. Swap the TC parts over. This will require removing the breech plug without damaging it. A TC wrench or similar is necessary, as is a real barrel vice. Re-tap the GM blank to the TC goofie threads. Install the plug. Swap over the rib, wedge slot, and sights. Blue. A competent gunsmith should be able to do this. A careful hobby smith should have no problems either. Bubba with a crescent wrench and machinist vice will botch it and ruin the plug and barrel.
After sorting the barrel. The wood can be reshaped to a more traditional contour. Excluding gunsmith services it should be do-able for $350.