There are three big main companies, and all I can remember out of those three is Pool (pool.com). Just for the record, Godaddy isn't one of them . They all cost 60+ for a successful backorder though.
If you want to spend 60.00 that is---If its a good enough name I guess that is not bad.
I have caught several from GoDaddy for 18.95.
You have to pay the 18.95 upfront but if they do not capture it for you---it can be used on another name.
Back ordering is cheaper at enom.com but not always successful, plus there is a minimu funds/verification requirement. I have been successful with snapnames, pool.com
I think if you really want to backorder a name you need to find out who it is currently registered with and then find out which backordering company is partnered with them.
It is very common for names to be "passed" rather than actually dropped.