I'd like a thermostat for my shop that will notice when I come in-- either by motion or the presence of my phone and turn the heat up. Then, either by sensing that I've been gone for an hour or two or noticing that it's past 6 pm, turn the temperature back down.

Any such beast for less than the $200 for a Nest (will a Nest even do just that?)? My shop is really well insulated and even when I forget to manually turn the heat down my gas bill is only $30-40 a month in the dead of winter, so a huge investment is a little hard to justify. Also I don't keep a constant enough schedule for the thermostat to "learn" my pattern. I need a simpler algorithm than that.

Suggestions welcome