Little trailers are popular, so your Minuet is probably more valuable than a 26' Argosy in comparable condition. "All original" in this case may not be 100% beneficial, because things like the axles and the 12v
converter/charger are better new than vintage.
Has it been used regularly? Or has it been sitting in a barn or (worse) uncovered in the sun and rain somewhere for years?
Post some pictures inside and out and we'll offer opinions, and probably the average of the opinions would be close to a reasonable guess, but remember that it costs us nothing to guesstimate, so our opinions won't have nearly the weight of an actual offer.
Welcome to Argosy ownership, by the way. I've enjoyed it so much I bought a second one recently.