Some brokers charge a fee just to list the property in addition to the commission. I would not list with a broker that charges such a fee.
There are several reputable brokers out there, all providing similar services. I would not hesitiate to use the Timeshare Store. I think commision, again depending upon broker, ranges from 10% to 12% on timeshares.
Everything is negotiable as far as whether the buyer or seller pays the current dues, or a potion thereof..who pays closing costs, etc. Your broker can advise you of the "norm."