250k uniques?
a) That traffic is not "safe" anymore than a fad-site is "safe". It will probably increase in the shortrun, but your site exists at the mercy of newscorp and its decision not to protect any IP and instead allow these sort of "editor" sites, even with their TM in the domain name. That and any day myspace.com could use its own internal people to create the best tools so that users no longer need external help/content - yet again, not saying it would happen, but to characterize the traffic as "safe" seems less than legitimate. </myspace theoreticals>
b) What stat program shows 250k uniques? Current hosting provider? Can you post screenshots of the main 4 charts if it is webalyzer or analog or any of the other main stats programs? I have sites that show in the hundreds of thousands of uniques, but it's because of all the dammed external calls that come in, not true visits. Not saying you have the same issue, just curious (And always good to see stats)
Valuation multiples?
a) 36 months is about right - but I usually try to push for 48-60 months for sites that have further growth possibilities immediately apparent.
b) Running with 250k on a "myspace" topic -
http://uv.bidtool.overture.com/d/search/tools/bidtool/ shows "myspace" and similar topping out between .10 and .25 . If you were doing parking (Which this will not be used for, I know), a 10-15% CTR would be good, considering the demographic of most visitors. Based on those numbers and parking, then $2,500+/month * 60 = about what you asked. However,
c) The real value to the buyer will be the increase in the value of his/her site from directing the traffic. I can't imagine he/she will see those kind of numbers, because the CTR is even lower on a content site, and the demand for those ad slots just isn't there ( check
http://www.googspy.com ).
d) Plus subtract a substantial premium for the inherent risk in the domain name being a TM issue (And UDRP-bait never looked prettier

).
15 years old?
a) Don't form an agreement with any 15 year old - no faster way to see your site disappear without your seeing a dime. His/her guardian/whatever needs to be involved (And if you're under 18, you need to do the same).
b) 15 year old with that much disposable income? To spend on a myspace site to redirect to his myspace site? Really?
13k on Alexa?
a) You're pointing that out as "not so great", right? I mean, i wouldn't turn down the opportunity to be ranked that highly on some of my sites, but that's nothing to start using as evidence of the buyer having tens of (errr... now I see "hundreds") thousands of dollars...
I don't want to be a "Debbie Downer", but this is one of those "too good to be true" situations all the way around.
I would love to see the sale go through and you walk away $100k richer, but if the situation now stands in the light that it has been presented...
Best of luck to you,
-Allan :gl: