What is the cheapest way to send a couple of axles 25-30 lb from Va to Washington State?
There is no relatively cheap way to ship axles that distance.
You might try Fastenal.
If clean attach a label to each and send them on the bus. Wrap them with shipping tape.
If you remove the gears then you can slip each one separately into a piece of PVC pipe and leave enough room to stuff some rubber carpet padding into the ends before you use PVC cement to glue caps on the ends. You can then send them via post office priority mail. You can figure out the cost by weighing the parts+axle. I ship driveshafts this way and they arrive OK. www.usps.com will allow you to ship them with a label clear taped around the pipe. I cut the label into 2 pieces and place them side by side along the PVC and I use 1" inside diameter PVC bought at most big box stores. Since the axles exceed 12" they will be considered oversize but the Post Office is about the most reasonable way to ship. You CAN also ship that same thing via UPS with a surcharge of about $11 but NO OTHER extra charge then applies so you get the large package and non cardboard surcharge included in that single oversize surcharge. Quote it both ways since sometimes UPS is cheaper. Local junk yards might have a better idea but I have never used them. Fastenal can be cheaper but usually only with pallet sized shipments.