I'd trust wot and cmos on this one. I've seen generic three letter .coms go for two to four thousand, i.e. qik.com recently sold for about $2,500.
Here are some three letter domains.
http://www.idomain.com/go.php?file=domainsearch.php&idx=2&c=156
On the other hand i've seen mixed letter/number domains go for as little as low to mid $xx.
I figured all number domains would be somewhere towards the lower end of this range unless there was some relevant market value. But, as I said, go with wot and cmos as my estimate was based on "feel" and theirs based on comparable sales.