I have been looking at refurbished desktops on newegg.com.
There's a few promo codes you can use on newegg.com - such as B2BWN4F111, which gives you $20 off
Nice! Where does one go to find such codes?
You can look at websites such as vouchercloud.com
Cool, thanks. Where else besides newegg is known for selling refurbished computers?
Try looking at discountcomputer.com
Ok. That is one I haven't seen before. Is that also a good place to find monitors?
Yes, you can find monitors there too.  You can also look at ebay
What is the most popular brand of refurbished desktop computer, Dell maybe? I'm thinking the popular would be cheaper. 
Dell is a great choice.  You can also look at HP and Lenovo - they're popular too