M.T.
It is always hard to find things to do that are cost effective,esp. in the winter. Here are a couple of ideas. If you don't know already, the Cedar Mill library has a great story time for the littlest ones - call them and learn about it because you will also meet many moms there and that can lead to playgroups, etc. Additionally, the Cedar Mill recreation center has great programs, and I know that Connestoga offers a baby art class for the littlest ones to which I took my daughter...and again met some great moms. If you do want to invest in some activities, I would highly recommend Gymboree at his age as well as Children Of The Sea swim school. My daughter did both starting around 7 months and thrived on the activity...as well as met more moms and kids. Finally, check out the website www.playgroupsusa.com. The goal of the site is to help moms set up local playgroups. I did it early on as well.
Have fun!