Can't comment on the climate in the US for teachers, but for the UK it seems to be a struggle to find enough people to make it pay.

I would suggest going further with the 'first lesson refundable' idea, and make the first one a completely free 'meet and greet'. Gives you a chance to meet the guy and find out where he's at. Unless he's a total beginner I would think it unlikely that you'll actually 'teach' him much in the first session...

The going rate in the UK is £15 - £20 per hour (about $30 - $35 ish I think). Only other thing I can think of is that on weekends in vacation time, people are likely to be busy / away just like you are. People who live near your holiday home might not be there on the weekends! Also, in my mind, a local teacher gives more of a sense of trust - local number on flyers etc... rather than a guy who lives the other side of the country the rest of the time.

Might it be better to sort teaching at this local store during the week, and just stay around there all day? Hopefully you'll get enough lessons to make it worth it and you only have to do the travel once rather than going to people's homes..... just a thought. You'd still have the weekends free for your plan as well...