I can't imagine adapters being cheapter. If I recall correctly, radioshack sell them for atleast a few bucks, plus, you have to take the cradle which is quite big...
the best deal for $ and portability is those sync/charge usb kit
ebay and search for something like
axim sync cable
goes from 4-7 bucks with couple more bucks for shipping.
for a few dollars more, you get the retractable cable.
fo 15 bucks + 5 bucks shipping, you can also get 3 piece sync kit, you can search for it like axim sync kit 3 etc
didn't post link because I am too lazy to actually read this site's policy regarding things like that
anyway, I don't have that psecific kit, but I have everything and they all work and as far as I can tell, they are all the same just different brand... all have the upside down plug lable...
I can't live iwthout these cables/adapters, my cradle is only used to charge my extra batteries.
edit: oh I use sync as search term only, they all sync and recharge through usb post on the computer/car/outlet etc.