Interesting search result; indeed sometimes in the UK one finds things that one doesn't find here in North America. That much said, again some care is needed. Those prices would most likely include UK VAT 17.5%, so for someone selling it in North America on a private basis, the relevant base value of a 1250 pound machine is 1068 pounds, or about 2100 Canadian dollars, or about 1900 US dollars.
This is not much cheaper than a new 4800 in the USA, and marginally cheaper than a new 4800 in Canada.
Because discontinued products tend to be discounted even if new, one could argue that in a North American context potential customers may see these prices as unrealistic, the immediate comparitor being the newer 4800 model.
I say "could argue", because in the case of this particular printer, there is a temporary advantage that could give it this kind of value: unlike the 4800, one does not suffer the nuissance and very high cost of flushing ink to change between matte and glossy papers. This is a HUGE advantage of the older 4000 relative to the new 4800.
On the flip side, the new 4800 is said to be somewhat more neutral in its B&W rendition, have slightly better colour gamut and slightly less metamerism (which was minimal on the 4000 anyhow); the emphasis is on the word SLIGHTLY. The 4800 also has less bronzing and gloss differential on glossy media (which for many people is no big deal because it hardly shows when you look at the print head-on). From my documented experience, the 4800 is also a more economic machine to operate than was the 4000 (ink consumption and cleaning cycles - though still not a stellar performer in these respects).
The advantage of the 4000 in respect of not flushing ink with paper changes is temporary, because Epson's main competitors are bringing product to market that do not and will not require this costly process, and do and will produce prints every bit as good as Epsons'. Though it remains to be seen, it would not be unreasonable to expect that these non-Epson machines may also clog less.
Bottom line Keltoid: if you want to sell that machine for a good price DO IT NOW. I think Epson printers are in for a rough ride in terms of resale value within the next six months.