I would say it's worth about $50-$100. I say this because it is a .com and only 4 characters long.
XTLO could stand for some meaning or even be a company name. It could be pronounced "X-Telo".
When I appraise domains, it is as an amature. I think most people just guess at domain values, because if you find the right buyer the things we use to estimate value mean very little.
I do think that domains like this that can stand for many different things are more valuable than some word domains because they are more "brandable".
Take the brand of "SONY" for example. The idea before SONY was the name "Sonny Boy" (I have no idea why...) and it was shortend to be SONY which I don't think has any meaning in any language, before they started using it...!