This has to be a mid $x,xxx + domain as it covers Tennis, Badminton and Squash Rackets.
It could also be used to expose and warn about 'Scams and Fraud' which are often refered to as 'Rackets'.
I'm sure if it were to drop at Snap Names today, Vaxis and Name Admin would be fighting into the low $xx,xxx.
Does it receive much natural traffic?
It appears not be parked or redirected at the moment but was parked with Domain Sponsor last year.
If the email came directly from the interested party, do some research before replying.
Check their phone number on White Pages and Google their email address and name to see if you can get any clues as to the type of person/company bidding.
Caution... If they are asking for an appraisal take care. There are many appraisal scams out there.
My personal way to reply would be something like,
"I have held this domain for many years. I receive enquiries every week. The domain is listed for sale at Sedo and/or Afternic. Visit this link, ........ to submit a formal offer."
List the domain for sale at Sedo/Afternic and set the minimum offer at say $1,000. If they bid at this price, you can then counterbid to say $5,000 and if they exceed this bid, you will have to accept. Alternatively if you don't counterbid, they can keep submitting further bids until you accept.
You could also submit this great generic domain to Great Domains and Moniker. A listing at Great Domains will strengthen the value of the domain and Moniker would be my choice of company to market and broker a domain such as this. Rackets.net is currently with Moniker so they would welcome the opportunity to market the .com
http://www.moniker.com/pub/Whois
It appears also that Rackets.net/.org/.info/.biz/.us/.de are not developed. The .biz and .us are redirected to Apartments.us
The only extension developed is rackets.co.uk so it may be worth contacting them.
Good Luck.
DOMiNIC