dam didnt know going co2 was so costly...
It doesn't have to be. Do you have a number in your head you hoping to stay close to? I could probably tell you if its a reasonable amount or not.
It kinda looks as if you may be trying to feed multiple aquariums from one reg. (just based on your question pic...) The more needle valves you want add, the more it will cost. Your post body can be the most expensive part of a build.