The above suggestions are good for what you want to use the bike for.
Being that you plan to ride it in winter and assuming that they salt the roads and sidewalks during the winter where you live...You are going to be looking at more maintenance, not less no matter how much you spend on the bike. The chain, chainring, cassette and derailleur are going to require the most maintenance in those conditions.
Go with cheapy bikes direct or framed bike for your purchase.