My R4DS review has a link to where I bought mine and it was free shipping but it took 4 week to get it. Although considering I've not had to buy a DS games since it paid for itself in no time so it didn't matter how long I had to wait. They shipped it all the way from Japan so that's why it took so long.
[EDIT]
Aw man they have the R4DS for less then when I bought it now...
http://www.dealextreme.com/details.dx/sku.1459
and that is with a 1GB Kingston microSD card. I believe that site also sells the M3 Simply possibly with free shipping as well.