Here is another option. Several of us have found some deals on metering valves and solenoids. Then the assembly parts can be found from a plumbing supply store, hardware store, Lowe's, Home Depot, etc.
Also, you can order your parts from Swagelok, Clippard, etc.
Left C is definitely right on. I dont know about the Fabco's, but im pretty sure any of the swagelok valves are going to be CRAZY expensive if bought in a store. With a little bit of searching and patience good deals can be found on ebay for metering/needle valves. While i was searching on ebay for metering valves, i had a pretty constant rotation of swagelok's in my watchlist. Some i just never bid on, and some i lost the auction by $.50 or so, but they seem to be in the $15-$20 range alot. I have put together a pretty high end pressurized co2 unit, and i have bought most of my stuff at a substantially reduced price just by bargain shopping and being patient.
As Left C mentioned, your best bet is to either order the needle valve and fittings from the aforementioned online store, or, buy through eBay. There are a bunch of great deals to be had (Left C picked up a Swagelok metering valve for $0.99!) if you are patient and bargain hunt.
The assembly parts (adapters, nipples, etc) can usually be found at a hardware store.
Yeah I think you all are right. Swagloks are kind of expensive on their website. I guess I'll pick up a brass barb and connecting hardware at Lowes or HD and use my Red Sea Needle Valve until I find a deal on Ebay.