Yeah, I would go to Accessories4Less for a great deal of gear, but you can find refurb gear all over Amazon as well. For things like projectors, there is stuff on the manufacturer website. So, that's always a good place to check. I know Dell, for example, has their 'OUTLET' store which has a ton of PCs at hundreds off that are basically brand new models that were returned and they have to sell as 'open box' or 'refurbished'.
So, it depends on what you are looking for, but I would start at the manufacturer's website, then go from there to Amazon or A4L and see what it is you are after and if they have it available.