How to track deals including daily deals?

I went on BoardGameOracle to check the price history of a game that had been Miniature Markets deal of the day not long ago. I was surprised to see that the special price, nor the steep discount it got for a weeklong sale a few months later, were shown in BGOs price history. Why wouldn't these prices be listed, and if this is a know limitation is there a different site to use for these special sale prices? I want to set alerts for games but if it wont include daily deals, special sales, etc, then I can't use BGO