A printer is definitely something you are going to need. You will want to print out any documents that are the most important to file and save. If you are selling something that you are going to be mailing to your customers then you are going to need to print out receipts to send with the merchandise.
A filing cabinet or a good filing system will come in very handy. You will want to keep all copies of receipts and any other important papers that are valid to your business. Make sure you keep any information about money you spend for your business for tax purposes as well.
File Folders are the best form of filing in a filing cabinet. They have tabs that you can customize so you can find everything where you put it quickly. You can come up with your own filing system that works for you.
Notebooks are an absolute must. You always want to have notebooks available for business meetings, when you have ideas, and to keep track of certain things. You may want to even keep notes on your clients or customers needs and wants as well as some key information that will help you remember who they are in the future when you talk to them. You will also want to keep track of any ideas you have for your website so when you start designing you don't go completely blank.
CD-R's are definitely a great tool for backing up your system files. The last thing you want is your computer to crash and you losing all your data. You will want to do back-ups on your files on a daily, weekly, or monthly basis depending on the nature of your business. Make sure you get a CD-R and not just a CD because with a CD-R you can keep adding files onto the same disk. This will save you space and money.
A fax machine is not absolutely neccessary, but you may want to have one in the future if you don't already. If someone you are doing business with doesn't always have access to a computer or email, they may have access to a fax machine easier. This way you have different ways to get the transaction completed and it makes things more efficient for your customers and clients. Remember we have to do business with the customers in mind and the easier it is to make a transaction the better your client base will be.
A scanner is a nice thing to have, but it is not neccessary. Depending on the type of business you are doing you may never need one, or you may need a scanner several times a day.
*tip* Getting an all-in-one printer, scanner, copier, fax is a really good thing if you do tend to need all these pieces of equipment. It will save you ink/toner and also be more efficient and a space saver.
Keep in mind the type of business you are doing will definitely have an impact on any other goods you may need to purchase or use. For example if you are wanting to go into photography you will need a camera. The information here is just what you will want to have in your home office or work space to get your business off the ground, and the most common things you would find in a home office.