All VOCALOID voices from V2-V4 are on sale. The physical versions ship from the UK, so shipping costs may be high for people who do not live in the UK.
Note that V2 products come with the V2 editor, but V3 and V4 voices can be used with the V5 editor, which can be found on vocaloid.com.
I would suggest not purchasing the V3 or V4 editors as of now, since they are being sold at very high prices compared to when the editors were the latest versions. If you would like to buy the V3/V4 editors I would recommend getting a VOCALOID3/VOCALOID4 physical starter pack off of ebay or amazon (for full price).