Hey Jhananda,
I used to work for amazon where I supported kindle customers--both reader and writer. Firstly, one can download the kindle reader for free onto almost any digital device. Secondly, one can send files like .pdf and .doc via email to an assigned kindle email address. When the device next connects to Internet, the file will become available to read through the kindle app. This has nothing to do with purchasing or making the file available on the kindle store--but it allows one to read their material on the kindle program before releasing it for sale.
Kindle books can be updated as often as necessary. So you could put one up in the kindle store *cough* fragrance of enlightenment *cough* and update it in accordance with your wishes.
In terms of price, I would charge what most other good selling books with a similar amount of pages in your genre are charging. I have purchased many meditation books, and a 250-350 page book by someone like Ajahn Brahm is about 10 bucks.
Lastly, Kindle is where I would concentrate efforts. People read on digital devices these days, and kindle is the easiest to do. It also comes with Amazons stellar customer device. They also have the best and most populated ratings system. Also, according to my last knowledge, the kindle store has the most customers and books out of any e-book retailer. There are many other reasons.
i personally search on google for a free PDF copy of whatever book I want to read. If it is available, I simply open it in my kindle reader. If it is not, then I purchase it on amazon.
I hope you find this useful. I believe amazon still has support for kindle publishers.