We used to have the AAA baseball team the Portland Beavers, but they left after last season. We do have a single A teams the Keizer-Salem Volcanoes and the Eugene Emeralds.
I'll have to go with the Lowell Spinners. They're the AA team of the Boston Red Sox. Tickets range from $5-$15, and they give out free stuff throughout the game. It's a great place to go during the summer to enjoy baseball.
I know some of the non-MLB teams that I have seen are the Worcester Tornadoes and the Pawtucket Red Sox (nicknamed Paw Sox), but I can't saw I am a huge fan of either of them. I also do not know what specific league they are in, but I don't think they are MLB.
Grand opening was pushed back once again, we'll just say it's TBA for now. We are still waiting on the completion of some custom development that has been in the works.