I am in a similar budgetary dilemma as yourself.
Here's what I am already doing, as it has already started to chill a mite.

I wore slim fitting lyrca/breatheable yoga pants (Salvation Army, $3) over my cycling shorts, and where the ankles flared, I wrapped one of those velcro straps (Home Depot, $1) around to hold them close to the ankle to avoid tangling into the chain.

I wore a slim fitting breatheable long underwear shirt ($25 at Kenyon mills but I just found one online for your for only $13.95 here) I had had from hiking under my jersey the other day. Kind of had that punk / skater look going. It was cute.

Socks? Go with alpaca socks. They are lightweight, breatheable, not scratchy, and come from wicked cute animals. Here's a link: sale on alpaca sport socks at Sierra Trading Post