Are you looking for a new- or recent-year FC20 then?
If you're looking for new, a large dealer like Colonial Airstream that has one in stock may be helpful for you. They may also have a lightly-used one available. A reputable dealer will provide you with a written description of the trailer's condition and should be amenable to an arrangement whereby you put down a deposit and go to inspect it, and close the transaction if it's as-described or get back your deposit if it's NOT as-described. Of course there can be snags in a process like that, but a reputable dealer should deal honestly.
It gets more complicated when you're buying from an individual. For the most part it's not difficult, but not everyone is as honest as we'd like them to be and not everyone has the same idea of "excellent condition" even when both parties are being honest. Your mileage may vary, as they say.
Il Carriaggio — 1975 Argosy 24 | Il Progetto — 1976 Argosy 28 Center Bath | WBCCI# 15566
He has all of the virtues I dislike and none of the vices I admire. — Sir Winston Churchill