I'm going through a similar language/platform selection process now - with many of the same constraints as you had. I too was leaning toward Python. One very significant hurdle with Python is that my application will be heavily text search driven and I haven't yet found a search toolkit with even close to the power that Java Lucene has. Using PyLucene would introduce the same resource problems as using Java for the web framework. In my case, the cost of more expensive hosting may be less than the cost of using a non-Lucene search option.