When I started, in my mind I "Needed" the following:
A good, 9mm Semiauto
A revolver (I wanted either a S&W or Ruger for reliability)
A semi-auto Rifle
a .45 Semiauto
and a 12ga pump.
At this point, that's exactly what I own.
A Sig P228R
A Ruger Vaquero (Old school, but the thing is rugged as hell)
Stag Arms Model 2
Mossberg 500 (A Marine Corps overrun)
I *want* a ton of other firearms...I desperately want a 1911, an MP5k or clone (pistol), an AK-47 type rifle (can't own one in CT chambered in 7.62 x39 sadly) a Desert Eagle....the list goes on.
I figure I have the weapons I could ever possible *need* in any sort of situation. My daily carries, my home defense, and my SHTF weapons. Someday I hope I have the financial means to get the guns I *want*, and start a collection of sorts. Until then what little extra income I get goes to ammo and range time.
I think if you can afford it without making sacrifices in areas you shouldn't be (i.e. food, gas, bills...) then go for it! Half the fun of owning firearms is the TYPE of firearm, and having the ones YOU want. If we lived in a war-torn country, then it'd be about utility. We don't, so get what you want, and enjoy them.