Is the finish acceptable? Not just the condition of the used pair, but the wood veneer or the paint choice by the original owner. Is it something you would choose for yourself? I'd be up for cherry in a used Treo CT for example, but I would pass on maple or zebrawood. At your level of cost you should certainly find the finish that calls to you.
However, if you save the 20k and go used, you can later find greater justification in trading up/over to something else. If you are a well-heeled experientialist taking a tour of the good stuff, then buying used opens more doors to whatever might call to you down the road.
On the other hand, if you are a perfectionist working toward the best of all possible systems in your space and setup, and you are not one to make changes every few months, then perhaps purchasing new is the best way to go.
Part of the fun is in the aesthetic of the choice, in my opinion.