Question about buying an aged domain name...

Domains that come with PR will often lose it once you have completed the transfer. Exceptions to this are domains that have existing backlinks that you can check on via yahoo (in the freshdrop panel, click the number in the yahoo backlinks column if it displays any) or one of the free backlink checking tools, although its not an exact guide it will raise the odds somewhat.

Freshdrop has a column that tells you if a domain's PR is fake Y|N - most are Y meaning that it is probably not going to remain intact once you've bought it. Fake PR can come from domains that have been pointed to by another domain with PR via a 301 redirect, or they had PR from previous strong backlinks that have since been taken down.

I've bought hundreds of expired domains this way and from experience most of them lose their PR, although as I gained experience I got a better "hit" rate by doing some research of my own on each domain before I bought it.

But at the end of the day, PR is not really worth a whole lot in terms of ranking a site in the SERPs. More important is the age of the domain, whether your keywords are present in the URL and whether the domain has existing backinks and their quality (if they're keyword anchored or not, or come from a niche relevant, authority domain). Also, a little luck is needed.

So good luck with your own search!