Well, I'd say it's pretty obvious that he wants it for his Amigas.
As far as where to get it, there are various stores that will do business by post from UK, US, or Germany,etc. Also, try ebay and other second hand sites.
First, you must determine what rom version you have in your machines. If original, your A500s may have 1.2 or 1.3.; if upgraded they could be 2.0 or 3.1 roms (I think the 3.0 roms only ever came out for the A1200 and A4000) I think the A600s came with 2.0 roms, but again could have been upgraded with 3.1 roms. (2.05 roms to be technical, compared with 2.04 roms for A500 and A2000)
Second, which Amiga OS do you want? 1.3 works with 1.3 and 1.2 roms, 2.0 and 2.1 works with 2.0 roms. And 3.1, 3.5, and 3.9 works with 3.1 roms. I think 3.9 requires at least an 020 processor though, can't remember about 3.5. 8-)
Okay try
here,
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here, or in Australia
here.