I hope this is in the right place, if not, mods feel free to pwn away.
KMart has an excellent deal on a good beginner's winter bag, or a target for a TQ conversion project. The Swiss gear crevasse 0F bag goes for around $50 on Amazon, $34 at KMart normally, and is $17 right now on sale.
I just grabbed two more. I have the same bag in a slightly different version, and it is very good for a synthetic bag under $100.
0F might be slightly optimistic, but it is quite easily a legitimate 20F.