If you want to buy from a US seller, I'd recommend buying from Yggdrizzle as he has a decent selection too http://stores.ebay.com/Retro-Saikou (although it'll probably be more expensive than Yamatoku)
Just make sure you have the right model to have the fastest load times for whatever game you're looking to run (for example, SCPH 90k models are fastest for PS1 games). Hope this helps.