I've never seen that big a turnover with kodiac's, to really see if they hold value. I have however seen several in the bargin cave and second hand racks at Cabelas. These generally list in the 600-650$ range. So I guess 500 is a good price.
It's a love/hate issue with that rifle..some guy's love a second shot,,some guy's hate that it's REALLY heavy.
As an investment? Well, you'd have to find a buyer to re-coup your money or make a profit. If your going to hunt with it you need to ask yourself where and how and what your going too hunt. Do YOU really need a second shot? 500 is a big step towards a fine ML rifle that can have some really fine acuraccy,,
If it where me I'd pass,,I'm a paper shooter and the biggest game I hunt is Whitetail and Blackbear. I've put in the time and money too know my single shot .54 well enough, if the first shot won't hit, I won't take it.
I don't need a second shot.