Ken and Rich,
I just purchased the Handel A-minor and F-major backing tracks from CatOnTheKeysMusic. These are very nicely done and sound great. They are inexpensive as you only need to purchase the piece you are working on, not a complete anthology. I paid about $7 for the two sonatas and downloaded immediately. I received multiple MP3 tracks for each movement, performed in each of 440 and 415 as well as a selection of tempos (I am finding the slowest tempos work for me; the fastest tempos look like they would suit a professional). So, one sonata gives you 50-ish MP3 file tracks from which to assemble your play-through. Each starts with a lead-in measure of clicks and holds tempo except for a slight slow-down at the main cadences. Since the realization is different than my Faber edition, I printed out a first edition facsimile from IMSLP to follow along with the figured bass. The description says that the recorded realization is “compatible” with this first edition.