Going from 450 to 490 or so (The min level for the transmute) isn't very expensive. And the xmute stays orange for a long time. (I think some of my alch's have went from 490 to 505 so far, just from making air once a day.) I sit them in Cenarion hold in Siilthus and fly them to the oasis thingy. Not sure if thats closer or further than Tanaris. Most of the time I'm lazy and just take the flypoint to uldum and back.