Always BUY the ML You Want After the Season Ends, that's when you find your Deals, the Dealer thinks they have you by the Powder Horn when you go in during the Season to Purchase one.
If you can make your Own Bullets and want a .45 than by all means buy one. But for the average ML shooter buying a .45 is not something they should consider, as like mentioned above the supplies needed for a .45 are hard to find and there's a ton of stuff out there for the .50