If it's a mix of letters and numbers, then probably low XXX. Still domain investors love 3 character .coms, so it should be easy to sell. Here's the most up to date version of the price guide for LLL and NNN domains: http://3character.com/priceguide.html
Is it 3 characters as in ABC.com or actually 3character.com? As the title and following comments make it a bit hard to judge.