That seems high to me. I've talked to a lot of sellers over the years though more from a buying standpoint than selling. My impression is that the standard is $1500 or 10% whichever is higher. I've heard lower numbers but I've only heard higher when the resort system is selling for you. If it's a broker, I'd look elsewhere. If it's the resort, they might get a higher price and justify the higher commision. DO NOT PAY ANY COMPANY AN UPFRONT FEE NO MATTER HOW CONVINCING THEY ARE. They'll even tell you they have a buyer for a great price for you, maybe even give you the buyers name. All you have to do is sent in $399 or so, of course, you never hear from them again or at least not in a meaningful way.
I'd look to posting in on TUG and the various other place you can do it for free or almost so. TUG is $10 for 3 months but if you join, you get one free add a year and the membership is only $15 anyway.
Regardless, prepare them for a shock at what they can get compared to what they paid or what they might be selling for new. I don't know Big Island prices very well but would assume $5000 is high for most 2 BR units there. I assume the other fee is charged by HI if you sell. The problem is I don't know if you'll have to pay that if you sell from outside, go to TUG and ask about all of your questions. Just don't go in a post like "I have X resort to sell at X price" type of thing, that's an add and shouldn't be on the BBS, t belongs in the classifieds. Good Luck.