Mobile Merchant Account

Hi
I am in 2 minds, the options for payment processing for my download products are:
http://paypal-ipn.com/
or
http://www.e-junkie.com/
?
i am confused why e-junkie charges by the month, and the other one above is a one of payment, maybe you get support and protection with ejunkie.
NOTE:
Merchant account is too expensive and costly paypal is cheaper & easier i have found, [...]