chaeto is the most forgiving--i've shipped/received it without any water in the bag and even used padded shipping envelopes sent USPS prioity mail. the others aren't that hard to ship, IME: a little more air than water in a sturdy box with packing peanuts/bubble wrap.
i always use fish store bags rather than ziplock bags--just about any major chain pet store will gladly give you bags if you ask the employees nicely. they might even give you rubberbands too so you don't have to worry about trying to tie a waterproof knot in the bag.
shipping during spring/fall months is best on the macro--less temperature swings--and means you don't need to use any heat/cool packs, which add weight and that translates to higher shipping costs.
bag each macro separately. that way if one
bag breaks, rips, etc. the others may not be affected
i've shipped and received lots of macro since i've been in the hobby. so long as the macro isn't subjected to really extremes in temperatures it's always survived the trip for me.
and last but not least, like with corals, making sure the person receiving the macro will be home when the delivery arrives helps too--especially for shipping in warm summer months macro can rapidly bake on a hot front, or back, porch.