Where/how to find closed auction amounts?

[Pfui]

I recently let a domain expire and just got a legit e-mail from contact-confirmation.com (a.k.a. Network Solutions) [robtex.com...] saying:

As a benefit of having previously registered a domain name(s) with Network Solutions, you are eligible to receive a percentage of the net proceeds that were generated from the renewal and transfer of the domain name you chose not to renew.

Apparently I'll get a (grande latte-$ized) check via snail-mail in six weeks.

What I'm wondering about is that "percentage of the net proceeds"...

How do I find out how much the domain went for, total, and/or the actual percentage amount? (Read: How much should I be kicking myself for not selling it on my own?)

I've only located sites to sell domains and current auctions, not sites with past sales figures unless the amounts were huge. Netsol proper is more self-hype than help.

Pointers, please? TIA

[IanTurner]

I'd ssay spam!

[Pfui]

As mentioned, the e-mail was legit. (I ran it through spamcop.net to be sure its headers and paths checked out.) FWIW, spam with similar phrases generally comes before someone lets a domain go.

[IanTurner]

If it sold through Sedo - you can usually check the auction history.

I don't think that it is possible to check auction history at NameJet, SnapNames or Pool unless you actually registered interest in the name.