Yes there is a fee to trade points for other than DVC resorts.
I do not know what it is currently. I think it may be different for different options (Interval International trade vs. Adventurer collection).
I think the fee was $75 last year when I made Disney Cruise reservations using our points.
yes I know, not the best use of points, but it was only a three night cruise and the difference between the money I could have got for renting out the points and the cost of the cruise was not enough for me to go through the hassle
If you join, you can always call members services and ask them what the current fee is. This is another reason why using points at DVC resorts is the best use. You don't have to pay the exchange fee.
Disney Collection - No fee for other WDW hotels and $75 fee for DCL.
Adventurer Collection - $95 fee (HAL cruises, bike trips, rafting, etc)
Concierge collection - $95 fee, minimum stays and cancellation policies may vary.
World Passport - $75 fee
Other DVC including VB and HH, $0