I had one for awhile personally, and it wasn't cheap but wasn't horrible--$49/month or something through a host agency. I can't recall if there was a sign-up fee.

Going through a host agency gives you all the functionality of your own access, except that you can't ticket on your own, but you can queue an itinerary up for the host agency to ticket. It's quite a bit harder to get access on your own without a host agency, and especially if you ever want to book/ticket your own itineraries, since you need E&O insurance, an IATA number, etc.

I later had one through work but we let it lapse as we never used it.