Howdy Mr. Keegan1696,
Well sir, since you are not currently reloading, I can not really argue with your logic. If you were forced to purchase all your ammo, yes sir, I reckon you would find the .38 spc loads (which can be fired in a .357mag, just not the reverse) to be cheaper to purchase.
But I have to be honest with you sir. I own 4 SAA clones, all are chambered for .45C, and they are simply a blast to shoot. There is nothing wrong with a mild load fired from a .45C in my view. Rounds at that level or lighter (many shooters actually used the .45Schofield load in the 45C, think .38spc v .357mag), filled up a lot of Boot Hills in the old days.
I know the .38 spc might be cheaper, but personally I would never consider getting a SAA to shoot .38spc loads in - after having fired a lot of target level loads downrange through 45C revolvers. I also like the feel of the history I have when shooting that caliber as well. But that is just my personal preference in a SAA revolver. But after shooting my first SAA clone, I was hooked.
Maybe the solution is for you to take up reloading again, if only on a small scale. Save the brass of the purchased ammo and when shooting if someone does not save their brass, ask if they would mind if you clean it up for them. You would be amazed at how quickly the brass could start to pile up with the right luck.
If you are interested, just yell or start a new post in reloading. I am sure several or our reloading members can suggesst space limited setups for you sir. Think back on how much fun and pleasure it gave you to shoot a nice tight group, and know you reloaded those rounds on target. Besides, all things being equal, reloading will give you far more bang for the same dollar, once you get past the initial outlay, which certainly does not have to be excessive.
Since you have reloaded in the past, you already know how many loads you can expect to get from either 45C or 38spc brass when loaded at target velocities.
I can not argue with your financial logic, but every other part of me wants to tell you - hey sir grab the 45Colt and never look back.
Good luck and let us know what you end up buying and give us a range report.
twoguns