Don't do space heaters - it's way more expensive. If your woodstove is old, get a newer one - the technology has come a long way in the last few decades. I switched from an old 70's "iron box" stove to a more modern (but not exactly fancy) hearthstone and it's a world of difference. Easy to control the heat, not get overheated, and easy to keep it slow-burning all day.

Also consider heat pumps. I got them this year. Elec bill has gone up a TON, but the oil bill is down by more than enough to make up for it. We used to get a bill for ~200g of oil a month during the peak of winter, now it's like ~80g (we still use the boiler for hotwater and to supplement the heat pumps), but our elec bill is nearly $400.