PHP / PayPal / Payment Integration

Hi Chaps,

I'm building a simple on-line clothing shop and I've  got to the payments bit and need a bit of advice.

I've checkedout  PayPal IPN and can figure out how it all links together, but I'm  wondering if there is something similar that doesn't redirect to the  PayPal site and resides within your domain.

Any guidence would  help a lot.

Cheers