A typical ecommerce solution includes the following components:

An online catalog that lists the products/services you are selling and their prices.

A shopping cart that collects the items a customer wants to buy.

An order form that gathers their payment information, applies shipping/tax, and summarizes the pending order.

Transaction Processing that subtracts payment from the customers account and applies it to your own.

Real-time transaction processing is provided via a vendor. Offline-transaction processing can be done by a merchant using a credit card machine. Of course, order fulfillment is also an important element of ecommerce.

An HTML form posts all of the information needed to process a transaction to your vendor's transaction server. Once the transaction server gets all of the transaction information, the transaction is processed. After the transaction is processed, it communicates the result back to your website, which communicates with the customer, and makes appropriate changes to your database (if inventory control is used).

How Much is it going to cost?

There can be a lot of hidden costs to ecommerce -- and a lot of people try to take advantage of people's lack of knowledge. Here are some general tips:

Setup fees. Most merchant account providers will charge a setup fee. This could cost $150 or more.

Transaction fees. This is typically a percentage of each transaction that is paid to the merchant account provider/credit card companies. Fees vary. A fee of 2.59% is good for online transactions. PayPal charges 2.2%. and no set-up fee. This has made it a popular choice for small businesses or those with only a small number of products to offer.

Monthly fees. There is usually some "gateway fee" associated with online transactions. $25 or less is in the ball park.