Best Equipment to buy

I am trying to figure out the best equipment to buy for losing weight and staying active. I am unsure which to get? I am thinking it is between a stationary bike or treadmill. My husband and I both enjoy the treadmill but the faster pace puts strain on my joints and causes shin splints and since I am overweight it is expensive to get a good treadmill that I feel will support me. We also both enjoy the bike but I am unsure if I would get a good enough workout using one or how it will affect overall calories burned apposed to the treadmill. I need a machine that can help me lose weight, get my heart rate up, be able to intensify as I progress, and not cost $600. Any help would be appreciated please and thanks in advance!! By the way, I have snow 8 months out of the year which is why outdoors is off limits most of the year though it is free it is inaccessible most of the time, and the gym here is very expensive since I am in the middle of nowhere. Thanks again!!