So I did some digging last night and found some options. Posting here in case anyone else has a similar problem. But first, responses...
Normally, Amazon does allow this kind of thing. And for most things, I would probably stick with that. But for some reason, they are not giving alerts for when a next gen console (Microsoft -or- Sony) will be back in stock. <shrug> So I cannot rely on that. Plus, it stands to reason that a wider net stands a better chance of netting a positive result.
Brickseek does look pretty cool and does have a 'Deal Finder' but just 'back in stock' isn't a deal. And it looks like you have to pay for a premium membership to get stuff like local alert. If I'm not willing to pay the scalper premium, I'm not willing to pay for a premium deal tracker.
But I *did* find two options... Zoolert.com and Popcart.com. Both are free. Both let you set an alert to be notified (in slightly different ways) when a product is back in stock (or has hit a specific deal). Zoolert will send you an email and/or a text. Popcart is a browser extension that will send you an email and/or notify you with a browser popup. Both seem to have good privacy protection policies (but I am no expert in that, so check for yourself) and only asked me for information that seemed relevant - like my email address and zip code (so they can check my local stores as well). If anything comes of it AND I remember, I'll return and report on how well they worked.