you should go to tdnam.com .Best place to buy expired domains. If you are interested I can give you a script which will check pr of the domains listed in tdnam.com
I think sites providing expired domain with PR ask for big $$ because they have to scan the www daily for PR which is costly. You can try http://www.premiumdrops.com But better go for some scripts.
Take a look at the following service http://mtw-ed.com where you can find expired domains with PR Also take a look at the following script http://cachelogic.net You can check PR,backlinks and alexa by clicking on "magnifying glass " on the left side of each domain