We talk about the cost of reselling a lot actually, but there are many different ways to do it, besides using a broker. My guess is that most experienced Tuggers sell their timeshares themselves. The only required cost is preparing the new deed - and some people even do that themselves.
Most of the scammers are not brokers at all - they are simple cold callers scheming for an upfront fee - with no intentions of selling your timeshare.
There is nothing wrong with using a REPUTABLE broker - it will cost you more, but they can walk you through the process and make sure everything gets done. However, for most resales today, it's not feasible because resale prices are below minimum broker commission, which is about $1,000. For a high dollar timeshare, selling for thousands of dollars, using a top broker makes sense and may get you a higher resale price.