Located in Australia, 22-250's is on the cheaper side compared to the 243 and 6.5 there will be no shortage of them im not worried about the cost of ammo either, also considering the 300wm at this point ive got loads of gear for reloading for 22-250/300wm and some stuff for the 243 so all are in question only thing that turns me off the 300wm is the barrell life, being a big sucka im guessing it wont last any where near the 22/250 but i could be wrong i need to do some research in my spare time and get the one that suits me the best...
I know the thread has progressed a bit but I just wanted to expand on the barrel life aspect. All three of your choices are barrel burners. 22-250, 243 and 300wm to a lesser extent.
I agree that a 243 sounds about ideal from what Im gathering about your intents and purposes.