Paypal:

Paypal is the easiest way to start accepting credit cards on-line. Paypal standard is free to set up and you do not need your own merchant account. Your clients can pay you with credit cards or e-checks and the client does not need to have a Paypal account to pay. Fees are 2.9%
+ $0.30
cents per transaction. Paypal is an industry standard and many on-line buyers are comfortable using Paypal and already have accounts.
Paypal Pro will allow you to take credit card payments by phone, fax, or mail. Website Payments Pro includes Virtual Terminal, which allows your customers the flexibility to pay you with a credit card offline, with no PayPal account required. Fees for Paypal pro are $20.00 per month plus 2.2% to 2.9% + $0.30 per transaction.
Mal's E-commerce:
Mal's is a remotley hosted shopping cart system that integrates with Paypal and other payment gateways. With the free version, you can accept PayPal, credit cards if you have a way to process them and offline payments like checks and money orders . For $8 a month you can upgrade your cart so it can integrate with numerous payment processors that Mal's offers. There are other fees associated with payment gateways and merchant accounts that you would additionally need to figure in to the monthly cost.
Solutions Cart E-commerce:
Solutions Cart is our custom database driven shopping cart that integrates with Mal's E-commerce and allows Paypal payments. It will allow you to update your inventory on your web site through an on-line administration panel with no knowledge of HTML and without the purchase of any web design programs. Features not only gives you inventory control by item, but also the option to set inventory quantities for the first option (size, color, style, etc.). Customers can search for products by category, keyword, catalog number and/or price range. It is fully customizable to integrate with existing web sites or custom templates.