The console will work with no problem outside of Japan, the power module inside is universal. They say that to attempt to dissuade exporting. The only thing is the backward compatibility is region coded as is DVD playback- you would still have to use Japanese discs for PS2/ PSOne games and DVD movies.
One alternative you could use is disposable credit card numbers. All of the major credit card companies now have this (visa, mastercard, american express) and can easily be used for one-time transactions. It's more secure this way as well- after you make the deal and it's authorized that card number is no longer useable for anything else. Need to top off? Just grab another number. A quick Google search will help find more information on where to get these.