1USD is 40.566BEF (Belgian Francs). The cheapest I found was 89000BEF (+/- $1960). Are you sure the $1620 is VAT included? I live in Belgium and can't find it anywhere at this price. If it's without VAT, the actual price will be 21.5% higher!
I heard the 24-bit converters from Roland aren't fantastic, but I have an XV-88 (no digital output) so I can't confirm that. That power-converting thing shouldn't be a problem, as the 3080 and my 88 automatically choose the right voltage (haven't tested it though) and I assume the 5080 will do the same. You only need a US-type power cord, the connection on the back of the 5080 should be standard. Concerning the memory: the 5080 already contains a few Mb's (I thought, don't know how much), but you can add a standard SIMM module yourself (up to 64 or 128 Mb, not sure).
Little question: where can I find the cheapest SRX-expansion boards? The best I can get is +/- $307...

Hope I could help,

Hans