The problem I've recently come across with the R4DS is their lack of firmware update has left more than a few newer games unworking. Granted, I've "upgraded" to a CycloDS (with 8GB SDHC FTW!!!) which, so far, hasn't had any trouble with any games I've put on it, even ones that won't otherwise work on the R4DS. I also like the way the way CycloDS' interface works, the firmware updating is a snap, you can have WAY more (unlimited?) themes on it than an R4DS (a mere 12, which is good for some but I like to show off my art)...uh, it came in a snazzy metal tin instead of a Matrix-inspired cardboard box...? I bought mine from DealWoot.com, they're in California and ship quickly (only took a few of days to process and show up in my mailbox) for about $50 (bought my Kingston 8GB SDHC card from NewEgg.com for $20-$25...can't remember exactly.)
8GB etc. is separate, CycloDS uses MicroSD for storage. So you have to buy the MicroSD separately from Amazon (unless it's in a deal). So don't put words together like that. http://www.realhotstuff.com/ http://dealwoot.com/
www.divineo.cn has it too for 48 USD. The 8GB MicroSD card can be bought in a regular electronics store.