Purchasing Dyes - Order or Buy Now?
I never pay “retail” for anything unless I really, really want it. That’s because I never sell to the highest bidder — I’m always a bit too greedy for that, so I tend to assume that even the low sell offers aren’t as low as someone is willing to go.
For my non-power-trading friends, I recommend a compromise: put in an offer in the middle. If you’re interested in a dye that is selling for 120g with buy offers at 100g (that 20g difference you mention), then lay down 110g. You should get your item reasonably quickly without having to spend time managing your TP offers. And you’ll still get a bargain deal.
(Just be careful to check gw2tp.com or gw2spidy.com or similar sites — sometimes there’s a spike and you don’t want to get caught in the middle of a speculation panic.)