I'm 65 & still handgun hunt,, a lot! Don't give up hunting if your age is the factor.
Now,, as for the guns. A few clues given cause me to think. You mention; "I'm sort of a accuracy nut." and that alone could be an issue with a fixed sighted revolver like any Vaquero. I have a Vaquero in 45 Colt,, that at first,, I thought might be me behind it. It shoots VERY tight groups,, yet they were "low & left." I had another good handgunner shoot it & he too got the same results. (He's still trying to pry that "bent barreled Vaquero" out of my hands!) Accurate as heck,, but not to point of aim. A trip to a machine shop/gunsmith,, and we altered the rear sight channel a bit to correct the left/right issue. I handload so elevation is correctable there.
You didn't mention if you handload or not. If you do,, then the cost of shooting it is almost the same for either caliber. If not,, ammo costs can be a much bigger factor in your decision. as noted,, .38/.357 ammo is often bound to be much cheaper than .45 Colt. Sadly,, unless you buy a "premium" grade ammo,, in .45 Colt,, you'll get ammo often built for much older guns,, and not allow the Ruger to truly show it's abilities.
Conductibility or desirability is subjective here. many desire the .45 Colt in a Vaquero,, and many have been built. The .357 is a quietly appreciated one,, and as such,, not as many built, and a bit more desirable to many.
I agree with the above statement,, "buy both" but understand the limited income thing too.
