Very tought question as you asked what we think is a good value. And yet, what is not stated is what we "get fer the money". So without know the benefits....hard to say the cost-benefit relationship is in balance.
I would say anyone who keeps koi can afford to pay $50 or more a year in club dues. ....but to how many clubs? If you join ZNA, MAKC, a local club, an Internet club...etc....the dues can add up to $200 or more.
So maybe a followup question is what would you expect in return from the club for those different dues rates.