Another needle valve that we can use for our purpose is the Ideal 54-1-11. The is a low flow and precise valve. Brass unit costs around $80 and stainless steel is $130. You have an option to have it chrome plated as well. This valve rarely shows up on surplus sites because the company is family owned and they don't make a lot. Remember the 54-1-XX model will work. Other models such as 54-2-xx, 54-3-xx are medium to high flow and they will be hard to control.
http://www.idealvalve.com/54-series-...le-valves.html