Yes, I know...my comments are definetely in the "wet blanket" category.
But gun owners need to be extra responsible in all areas, in my mind..."home finances" is an important area to be responsible in...
I have more than one gun myself. And MANY times I have had the urge to buy this or that. Had to stop myself, get other priorities done first.
Alternatively...guns are tools, some better for some purposes, some better for others. You could reswizzle your collection...I've done that as well.
Sell the stuff you don't shoot. Keep or buy stuff you will shoot more of.
If you have a Kahr K9, do you really want an XD? (or do you just want to try one out for a little while...much less expensive to find some range that rents them...).
I've never been enamored with .22LR pistols...don't seem like much of challenge to shoot...too easy. Boring. Inexpensive ammo, however...nah, still too boring.
New rifle? C'mon, which one that you already have do you shoot the most? Do you really need another? Which one really goes to the range more than the rest? Are there several that are dust collectors?
Simplify. Shed the ones that don't get used.
My first AR-15 was a 16" barrel flattop. After I shot it for a while, and learned more about AR's, I figured out what I *really* wanted was a 24" free floating barrel AR with a bipod and a nice scope. So I rebuilt the one I had, rather than get a new one. Sold the old parts, bought new ones. Cost of the parts sold nearly covered cost of new parts, incredibly (thank you ebay). Did it all without spending additional dollars other than my initial investment.
By now, I'll bet your much more knowledgable than you were when you bought your earlier guns. Now I'll bet you know what you really want/need/can use. Redo your entire collection, but do it in such a way you keep your $500. That might mean owning fewer guns....but they will see more use...