Since injuring my shoulder, I want to take things lightly. I see many Bowflex's and crossbow's on craigslist for sale. Obviously, I can get the crossbow a lot cheaper than bowflex. After doing some comparisons, I only see minimal differences between the 2. Except, I can get a crossbow (used) for about $100, compared to a used bowflex at like $300. Anyone have either machine?