Might have to try that Eagleman...
Anyways, if you're trying to save your money, I recommend that you buy one primary weapon for a week at a time...you do save a little money by buying weapons for a week at a time, so as long as you're sure you'll play enough to get all your money back (or even more would be better) you should buy for a week at a time...if you know you won't have much time that week, just buy daily still when you know you'll have time to get your money back...also, stick to weapons that aren't too expensive, like assault rifles with scopes that are under 1k together...
And if one primary weapon isn't enough firepower for you, it isn't too much more money to add on some grenades or something else cheap...just make sure you can make the money back before the weapons run out!