I've been using Indeed a bit for my own needs and also for some clients.   Although not as effective as Facebook, I find it the cheapest way to get matching candidates.   

That seems to be the consensus judging from comments by recruiters over at Recruiters Who Actually Make Placements:

Nanette: "I had a LI job slot for a while...very expensive and not successful. Same holds true for CB and Monster. I have 20 ads with CB I need to burn up by May. I will not purchase anymore."
Jeremy: "It is true that Indeed is the #1 site for job seekers today. It has surpassed Monster, Career builder and Dicele combines and helps your Brand and SEO strategy."