The number varies. I dig through a large list - around 800 to 1000 to start (depending on the category) and weed out the ones that do not accept free links. Of course if you're willing to front a budget I can include various pay sites as well.
Once the initial submitting is done, I continuously watch for new sites.
The main advantages are that I do it manually (by hand - me personally), I make sure it is submitted to the proper category - which is benefit over automated software, and I keep a record and status of whether it's been approved, pending or rejected, so as not to duplicate submissions.
Like I said, this deal is meant for people who have better things to do with their time, as I've developed a rather quick way to gather the data I need and submit in a timely fashion - while still retaining the human element.
As for the number of links ongoing, it depends on how many new directories get discovered and passed on down the chain to me. My best guess is approximately 100 per week.
If $50 at sitepoint still sounds like a better deal you, then go for it. I'm looking for people who want personal attention and possibly develop an ongoing relationship, seo consulting, and web development expertise for their site. I would be discussing techniques, new strategies, etc. over the phone on a weekly basis.