Do you have any idea how much control I've been exercising lately with these 'low hanging fruit' topics you guys keep putting in front of me!?
[
] My goodness, it's almost too easy sometimes. heh
For what it's worth, just buy a $30 moisture meter off Ebay. Accurate or not, once you figure out the scale, it doesn't matter what the numbers say once you get used to what's dry and what's not.
Most of the cheaper moisture meters aren't real accurate, but in my experience they're at least consistent, so when it says 6% moisture, it may actually be 9% - the thing is, once you've figured that out, all they are is a dummy measuring stick for when something's turnable or not, as long as you know how to read your particular meter.
I wouldn't worry too much about them picking up moisture if they were dry enough at one point. Unless you're storing them in a fish tank or something, there's not too much atmospheric moisture that's going to make a difference if they're inside a sealed tub.
That being said, if your shop tools are sitting there growing rust in their new environment, I'd just turn a few and see what happens.
The microwave trick is good, too. For me, though, I don't mess around with weight too much. Stick it in there for 15-20 seconds wrapped in a paper towel. If it's steaming, or the paper towel feels slightly damp, just run it through a few times until it comes out warm and dry.
Hope that helps.