However I did get burned on one situation. I signed the client, he paid a couple months down and then began making payments and was very consistant – no late payments and I never had to remind him. However when he had about 4 months left, he ended up getting divorced, closed the business and moved across the country. Never was able to track him down – I actually never really persued it. I did some checking around but never turned him over for collections.

- Anything ending in $7.50 is a good number to use, although I’m not sure why: $47.50, $97.50.

Taken from wilsonweb.com:
Odd-even pricing takes advantage of human psychology that feels like $499.95 is less than $500. Studies of price points by direct marketers have found that products sell best at certain price points, such as $197, $297, $397, compared to other prices slightly higher or lower. Strange, we humans!

http://www.1shoppingcart.com lets you set up recurring billing. You can set up the installment amount and number of installments for any product you offer. It is a very nice and intuitive system, and includes tutorials. I use them (and receive no payment for making this recommendation, nor am I an affiliate).

Alternatively, if you build a home grown solution, make sure your hosting company supports “cron job” billing. For instance, I know that http://www.lunarpages.com does, so long as you have a dedicated server. They don’t allow the wget command (and here I’m getting out of my range of knowledge) unless you have a dedicated server.