Not sure what's your point, but trying to answer your question, pcanywhere has a thin server feature. It's called "quick connect and deploy" and let's you install a 'thin server' on each machine you want to connect to. The license costs $20 I believe.
So, depending of the market segment your customer are in, that may not be an outrageous cost at all.
Now, even if you had to pay for a license of pcanywhere, which I don't think you need to, but let's suppose you do, that's about $200, prorated in one year, it's less than $17 monthly, and the license doesn't expire after 12 months indeed, but let's be conservative for a while.
Are you telling me that you spend less money than $17 monthly if you just drove/flew to their place, or that $17 monthly turns your software into a not affordable items? ;)
Now, one really cool thing we also use here with excellent results, is gotomypc.com, it's just great.