If you're a retailer, looking for POS hardware, there are some things you should keep in mind as you shop.
Start by looking at the software you're using. This will limit what hardware you can buy. This software includes both the POS software you're using and your Operating System.
Most POS companies have a recommended hardware list. You should definitely look at this before you buy anything.
If you find a good deal on a piece of hardware that's not on this list, email or call the company. They may have tested it and just not updated the list.
Finally, make sure that the hardware will work with your computer's Operating System. For instance, if you're using Windows 8, make sure it'll work with that. If you're using OS X, make sure it will work with that.
If you can't confirm that the hardware will work with your software, make sure that you can return the hardware if you have to. You don't want to get stuck with something that doesn't work with your POS system.
What type of POS hardware should you look for? This also depends on your POS software. Different POS systems let you use different types of hardware.
For instance, if your software lets you print and scan barcodes, you should look at buying a barcode printer and scanner. Most programs will also let you print barcodes via a laser printer, so you may want to buy one of these instead of a barcode printer.
Depending on what you're selling, you may want to buy a receipt printer. These print receipts onto rolled paper. Most POS software will work with these. You can also usually print receipts onto letter or A4 paper via a laser printer. If you have a lot of information you want to share via your receipt, this may be the way you want to go.
The software may or may not be able to "pop" the cash drawer automatically after certain types of sales. This will depend on what software you have. You can still buy any cash drawer you want, though, and open it via the key.
You may also want a pole display or a small second monitor to display information to your customers about their purchase. These may or may not work with your system. This is something you'll have to check with your POS software company.
Finally, you may want a credit card reader, especially if your POS system offers integrated credit card processing. If this is the case, the software company will probably recommend or even give you a reader.
In the end, though, while shopping for POS hardware, it's important to keep in mind that the hardware you can use depends on the software you have. Make sure that whatever you buy will work with your system and that, if it doesn't work, you can return it for something else or a full refund.