They do require a sub to make for a full range sound.
Finding speakers that are sold singly is a rarity and if you can get past that, here's some suggestions. ...but they are only sold in pairs I believe.
You might also want to consider, in descending price order, Wharfedale Diamond 220, Elac B5 (or 5), or the Philharmonic Affordable Audio Monitor
Since you're going by what you read and other (unknown) peoples opinions, there are many reviews of these on the interweb.