You have to be very careful with this, because many of the folks who will present themselves to you as "brokers" are actually just scammers. They charge a high upfront fee, and then never sell your timeshare - it is an extremely common scam.
Anyone that you received a cold call from, is probably a scammer.
Reputable, well-known brokers, usually start their fees at about $1,000 minimum. But for a more expensive timeshare, they charge a percentage - like a real estate agent does.
A reputable broker deducts all the fees
out of the proceeds of the sale.
Anyone that wants to charge you an upfront fee is probably a scammer.
There may be small local companies in the resort area, that may charge you less, but again - all fees should come out of the proceeds.
It is possible to sell your timeshare yourself, but in all honesty, unless you own one of the top resorts (Marriott, Westin, Hyatt, Hilton) etc., your timeshare probably has no resale value. Most timeshares sell for 0-10% of the original price, on the resale market, and there are some that you can't even give away.
If you find yourself in the position of owning a timeshare with no resale value, it may be possible to give your timeshare away, if it is completely paid off. MORE INFO.:
http://www.tugbbs.com/forums/showthread.php?t=132509
***I see that you are actually looking to
buy a timeshare - the broker's fee will be paid by the seller - not by you. However, it does add a significant chunk to the price, which is why some people opt not to go through a broker.