For the newest releases in Japan such as "Honeycreeper" and "Hit and Fun"
or the Japanese version of their CDs I'd
recommend either YesAsia
or CDJapan.
For new copies of the US releases I tend to go with
Amazon.com.
If you are content with used copies I'd recommend either using Amazon's used dealers
or trying eBay.
Prices tend to vary. I'd recommend only buying from long established dealers
with very high ratings. Sellers on eBay also occasionally offer the older Japanese
releases and collectables. You can use the link below or the following eBay search for
amiyumi.
If you're a fan of the cartoon Hi Hi Puffy AmiYumi then Amazon.com and eBay are also a good bet
for new or used copies of the DVDs Rock Forever and Let's Go.
Another option is to use a download service to buy specific songs.
I've used Rhapsody for songs
like Girls Just Want to Have Fun.
I haven't used the following sites but they also have Puffy music:
According to Amazon.com (I guess I believe them) Puffy submitted the following
List of Music You Should Hear
recommendations on July 29, 2005. It includes the groups Hole, Queen, Jellyfish, Red Hot Chili Peppers, Nirvana, Tamio Okuda, Ringo Shiina and Hi-Standard.