Just for the record, I would advice anyone getting into this business to have this as part of a portfolio of services, rather than just a single service on its own. This area of work usually comes 'hand in hand' with other development services (with rare exceptions), and would be difficult to establish cash flow with just this service on its own.
As for pricing structure, your experience and knowledge should be reflected in your price. Personally, I would advice 3+ years for Django and 5+ years for Python/Stackless, anything shorter than this and it would be suggested that you don't really meet the minimum criteria for calling yourself "a professional" in the field.
However, sometimes years of experience really doesn't count for anything, it all depends how much you love the language, and how much you have learned along the way. I had been a commercial PHP developer for almost the same amount of time I was doing python (py 2005 / php 2007). But let me tell you this, my PHP code was absolutely atrocious. I don't know why, but me and PHP just never got along. Where as with Python, my code was constantly getting better.
Remember to just always be honest with yourself, and don't offer this service unless you are *really* good at what you do.