Hi Will,
I'm no expert, but on a small scale you'd have to go for something you could attach a premium to - something unusual or organically raised etc.
In my experience, on a small scale level there's not much room for profit - it's only when you start to talk about buying feeds in bulk (or growing your own which would obviously eat into the amount of available land) or intensive rearing for a quick turn around, do you have room to drive down costs and get a profit.
I'm not sure this is going to be the most helpfull site as most of us here don't keep animals purely for profit (in fact I doubt whether any of us would want to consider if we do indeed make a 'profit' - as I suspect the answer would be a resounding NO ! just tasty meat and the enjoyment of raising our own animals)
I suspect on a small scale for maximum return you'd need to consider chickens or turkey's as they grow quicker, take up less space and don't cost that much to feed, but by the time you consider housing, fencing, vermin control etc you'd possibly be onto your 3rd or 4th 'batch' before showing a profit.
Hope this has maybe helped a bit ?
Good luck
