yes, a lot od pre registered domains are worth $60 backorder. Most of the domains loose the pagerank but they do not loose the links that other websites might have to this domain, so eventually, after some time, the domain CAN gain the PR back.
Alexa does not send you traffic, Alexa is just an approximation of traffic ranks, so if a domain expires, it's long process of redemption, pending delete, final delete, back order and then you get a new website live, this process extends over 2 months approx, 50 days for sure in most cases, so by that time domain has lost the traffic and a majority of the search engine rankings.
They can be regained, to some extent, if you have the old website, and are able to get back any dmoz/yahoo listings if at all they existed.
Good Luck. Let me know if u have nay more SEO / Link Pop / Pagerank questions.