shopping cart integration

[swissbeets]

ok i have posted this on numerous forums and done as much reading as i possibly could find but still no prevail

 

i have a shopping cart that works perfectly for what i need, it saves everything anytime a user clicks add to cart onto mysql server with a primary key that is unique to anyone who clicks the button and then saves it.  so basically i query the database for this unique id and get all the info i need for  ashopping cart.    but now i need a checkout. i do not want ot make one because of the liabilities but can find nothing that will work with my ideas?  if anyone has ever used google checkout or paypal it would be greatly appreciatted just a little bit of input since this is my first ecommerce site.