I started out with a Cabela's clearance jacket and snow pants - it worked but I always ended up wet either from snowdust melting or sweat not being able to get out.
Now I have all Klim and it is great. I should have bit the bullet and done it from the start but it is expensive. No water gets in but it breaths. The layering system works like a charm - feel a little cold add a layer, get too warm take one off. For me a long underwear top, jersey, tek vest and outer shell (nylon/gortex with no insulation) keep me warm down to about 0F. Add a fleece jacket under the shell and I am good down to -30F.