To the OP, a few more thoughts.
As I said above, my financial situation is as such, that has to save up a bit at a time for my bigger purchases, and don't usually have the disposable income for my firearm sickness.
So, I absolutely feel you on the fact that some of us have to adhere to a budget.
Now that I'm sitting with the rifle of my dreams, with everything excactly how I want it, having spent the hard earned cash, I DO NOT regret waiting the extra few months and saving a bit more, because now I know I've got the best rifle I can afford in the configuration I prefer.
Please don't take offense, but if $500.00 is a hard and fast budget, maybe another longgun is a better choice? Depends on your uses, but maybe you'd end up preferring to have something like a 10/22 and tons of cash left to mod it, or maybe really nice bolt-gun...rather than having "part" of a gun sitting around.
Personally, I was SUPER stoked to have my lower sitting under the Christmas tree last year. It meant that I was then able to seriously start shopping all the options, and making decisions about the direction of my build.
But that's just me.