My best site has a PR of 5, but I think it’s going to go up fairly rapidly.
When someone asks me to do a link exchange, I’m generally willing to do so regardless of their PR. My thinking is that if they’re doing the work to get link partners, their PR is going to go up and I’m going to benefit from that.
When I look for partners to link with, I tend to discount sites that don’t have a PR of 3 or 4 or better. i.e., I don’t turn people away when they approach me, but I don’t necessarily seek out partners with low PR either.
Hope that’s helpful!