At the moment launch of dual layer products seems imminent rather than actually having happened. I think that's just as true in Japan as US / EU, but I could be wrong.
Certainly several companies have announced (via various routes, including FCC filings) dual layer products - these include Sony, Philips and NEC (there's another company that's made a drive available now for which they have said a dual layer firmware upgrade will follow - I forget which one it is). I don't think any of the drives are currently shipping with dual layer firmware installed, though.
Even if you can get a drive capable of writing DVD+R9, you almost certainly can't get DVD+R9 blanks.
Personally, I'd wait a while for things to settle if you want dual layer. There may be problems with the first generation of dual layer writers.
If single layer will do, you can pick up a NEC ND-2500A for around 60 pounds here in the UK now (blankdiscshop.co.uk have them at that price). It might be possible later to do a (likely unofficial) upgrade to the ND-2510A firmware, which will allow DVD+R9 capability. The FCC filing for the ND-2510A is based on it being the same drive, apart from model number and firmware, as the ND-2100A (the DVD+R only version of the ND-2500A). However, there is some debate as to whether the ND-2510A will actually have a different optical setup. It's also possible that only drives shipped as ND-2510A will have the necessary calibration data for dual layer writing.
I suspect, in another few months, that it will be easy to get a DVD+R9 capable writer for less than 100 pounds here in the UK. Media, however, seems destined to be expensive and in limited supply for quite some time - it may be hard to get hold of until September or so.