I have the chance to take my pick of 3 different regs. any one for the same price. They are an Atomic B2 with about 20 dives on it, a Zeagle Flathead 7 with Miflex hose with less than 50 dives or a ScubaPro Mk25sa/S600 with 10 dives. I can take my pick for the same cost. What is a fair price and...