if you are writing info articles on your site, which are considered like news articles, you can use pictures as editorial pictures and you buy them as editorial from stock sites or you can use pics from manufacturer with their permission (just mail them). however, you can't use pics from other sites (unless that pics are also given with permission from manufacturer or under creative common license)
you can use, without paying or manufacturer permission, pictures under cc license, but you have to give credits (put source and author in caption of pic). those pics you can find on wikipedia or similar sites or other info sites like yours and you can use them (with caption!)
so, if you are buying pics, use stock sites like
shutterstock which have bulk options for monthly/yearly download and almost everything covered and you can get editorial licence. shutterstock is one of the cheapest and biggest. and I'm selling my stock work there
... unfortunately, don't have pics of routers for you.
on the end, you can use your own pictures as you own copyright for that and for editorial (newsworthy) use you do not need permission from logo owner (manufacturer), but as you said, that is not option for you (or you can for routers you can photograph on your own)