Most economic large caliber? 22lr?

I am interested in getting a new upper in 450, 458, 50 etc but looking at the prices they are pretty spendy. I havent even looked at ammo yet. What is the most economic of these expensive uppers as far as up front cost and ammo etc? I would really like a 50 BMG but cant see that happening for a while.

What a 22? Any good deals on 22 uppers? I have never had one one so I dont know the best way of going about this.

I have a MODEL "1" 22 LR dedicated upper from Texas.
I would check out Spike Tactical,or Tactical Solutions.
Mine has about approx. 35 thousand rd's fired.It does not like thin,notched match grade hammer's use mil spec hammers.FEDERAL bulk pack fires reliably,but is inaccurate .Works good with subsonic or CCI.Most important 'CLEAN IT OFTEN",including the extractor and firing pin hole;or will result in slamfires or doubleing.
Spike's uses extra strong firing pin's,since I've broken 2 already.Also have broken 2 RRA Match grade hammers,plus another make called J&P?