Quote from Scataphagos:
1. You can squirt compressed nitrogen into an open bottle to replace air/oxygen, then re-cork quickly. Should be available from liquor store or online.
2. Boxed wine. The bag inside collapses and doesn't allow oxygen to enter. Box instructions say, "for fresh taste, consume within 3-4 weeks of opening" (I have no wine palate myself, but my former next door neighbor is a sommelier, and she says some of the box wines are very good. I serve some at neighborhood parties. MUCH more convenient than bottles.)