I work as a technical-SEO consultant and we had the funny idea of checking all these domains about a year ago: None of them are worth buying! None of them has any SEO-potential!
- the page-rank passed from milliondollarhomepage.com to these domains is minimal (huge PR divided through tons of links is worthless)
- domains expired for a long time get some sort of "reset" from Google (we experimented with this - strong domains last used years ago do not rank faster than "fresh" domains)
Therefore, in the case of PageRank and SEO-potential: It is better to try to buy domains of local companies in your area that went out of business. These are much stronger.
And in general: Buying old domains for backlinks is a waste of time. Getting high-quality backlinks from legit sites and improving your own domain in regards to technical optimization and usability is much more effective - and scalable.
Edit: Improved formatting