AreMySitesUp.com recently rolled out a more sensible set of premium plans at $25/year to check 25 sites, $50/year for 50 sites, and $75/year for 100 sites.
Of course the nice thing about the way AreMySitesUp.com handles sites, is you can have it look for specific text, so not only can I check to see if brian.carnell.com is up, but it is also fairly easy to monitor to make sure the site is not only up, but that the database hasn’t crashed, etc.
Now if they would only add subdirectory support so I could also reliably test if brian.carnell.com/gallery2 is also up and working properly.