By selling through your own website, you can forgo the sales commissions, but you will need to set up the actual online store. You can do this by using free, open source e-commerce software like Zen Cart or Pretashop or you can hire a web developer to do this for you. Setting up an e-commerce system does take some technical skill, so if you don't feel comfortable doing it yourself, hire a professional (keeping in mind that a web developer may charge $50-$100+ per hour).
If you currently accept credit cards at your brick and mortar store, your credit card processor can most likely also process your online sales. If you don't have a credit card processor, look into services like Google Checkout and Paypal. These services are very easy to use and implement on your site, but also be sure to compare their transaction costs with traditional credit card processors.
Once you have considered the costs of processing payments, you will also need to consider shipping costs. Rates can vary significantly between shipping carriers. Be sure to research prices and services including shipping insurance. Also, ask each shipping carrier if they provide free shipping materials. By using a free box provided by the shipping carrier instead of buying boxes yourself, you may save $1 or more per shipment.
Since you (or an employee) will be spending a good deal of time at your computer once you start selling online, there are some equipment issues to consider. Is your computer able to handle your ordering system? Having a slow, outdated computer can lead to ordering system crashes and lost orders. When choosing a new computer, be sure to also buy a large monitor since you will be looking at it for long periods of time. When packaging your products, you will need a laser printer to quickly and professionally print packing slips (as well as sales reports for your own records), a scale for weighing packages, and a label printer for printing postage.
As an agricultural entrepreneur, have you started selling your products online? If yes, how has selling online changed your connection to customers? Have online sales affected brick and mortar sales? If you have not considered selling online, what has stopped you?
