I think it is a reasonable price. If you really don't need the money, I wouldn't sell it just for the sake of making a sale. If you need the cash for other things or other renewals, then it isn't a bad sale.
The term has commercial appeal, and you say it has a large number of searches, and it's a big term especially for the female market. For a company that is in this market, $600 would be a small price to pay. I can see this domain being used on an infomercial, for example, for a new type of hair dryer, or in an ad.
I am surprised this term outranks 'blow dryer'. 'Hair dryer' has almost 6 million returns in Google, 500,000 global searches per month and 22,000 Canadian searches per month. Ad competition is medium to high. Product domains seem to be in more demand lately, because it's easier to set up an online sales site now through Amazon or Shopping.com, and this is a product I could see people readily buying over the internet.
---------- Post added at 12:47 PM ---------- Previous post was at 12:45 PM ----------
In short, $600 is a decent price if you need to make a sale, but personally if I was in this position and had to sell it, it wouldn't be a sale I'd be happy about.