Dex alone without enchants won't get you anywhere... trust me, I used to believe the same thing, since I didn't want unnecessary expenses or to blow up my cute dresses. However, then I saw people with 150 dex out-damaging me at 300 dex, so something had to change.
Either way, nowadays I have 490~500 base dex when I'm ~level 80 and my damage range without equipment on is ~270 and lackluster critical to go along with it. With my gear on, it's more like ~360 max and ~125% critical without trans... notice how significant enchants are?
And yes, that is with a regular Long Bow (Glorious Caliburn) and no food spam... Long Bows are actually the best bow you can wield short of a Highlander one (unless you need Wing Bow crit).