Agree with the above.
You don't need to buy the domain to target the term. If you want to make a website for a chat room, use a more memorable domain and then use the keyword tool to find out which keywords to target and get traffic from.
This forum is great for newbies to learn, but be careful purchasing domains without being confident that you have the knowledge. Perhaps see if anyone wants to purchase domains you have bought at anything above reg-fee before registering any more?
Also, browse around the forum and DNJournal/DomainPrices to get a feel for the type of domains which are both selling and receiving interest/offers (however, take any threads which say "offer received" with a spade load of salt, as some members here are getting a bit of reputation for doing that).