Well, you'll be able to afford to shoot the Python a lot more than the Casull. I have a 454 as well and as much as I like it, she costs a bit to keep her fed. Unless you are looking into reloading, be prepared to pay about $1.50 per round for factory 454!

At least the snake will eat both 357 and 38spl but I would look around a bit as the price seems a bit rich for the Colt

. If you are just new to handguns, best not to start with the Casull as it'll hurt after a few rounds and that takes the fun out of it. Oh sure it makes a bit boom and the flameball is cool, but it comes with a price.. Give it some more thought..
Cheers
dB