You don't need a domain with PR. Google hasn't updated that metric in nearly 3 years. It's a pretty small factor in picking out a domain.
As for $1-5 domain names, there is some "specials" offers on some registrars for cheap .com domain names, but they usually come with higher reregistration costs and they usually make it a pain in the ass to transfer the domain to a new registrar.
Depending on your project, namecheap (I'm sure other registrars do as well) has some of the new TLDs for $0.88 for the first year (then normal registration fee the 2nd year, which for the new TLDs is more than a .com).