score:2
The price alerts are just another source of information. More information can only help when it comes to purchasing airfare. You might eventually get spam but I have price alerts from three sites and they have not sent me many so far.
Searching for the flights yourself will lead to the same results and potentially an even better fare, just as you are likely to miss on a good price. These alerts are not sent the instant a better price becomes available but at a certain scheduled time based on prices that were recently found. This means that by the time you get the alert, the fare might be gone. It is also less good for travelling with family since the ones I use (not sure if others do it differently) alert about there being a spot left but even when you try to book, there is a only one seat left note or something similar.
In your situation where you know your dates months in advance and those dates are not very flexible, I would expect these types of alert not to find many better deals than what you get. Prices do go down though but often these come at a cost of a more lengthy and complicated route.
Upvote:1
I finally decided to use price alerts to see what would happen. I get alerts when the price goes up or down. More often they go up, but they occasionally go down. In rare cases, they go down significantly, but that bargain fare typically lasts only a day or so.
Just today I got an alert informing me that a flight I had inquired about dropped over $100, from $400 to $300. I've concluded that it may be worthwhile to sign up for an alert and wait for a price drop, but you are taking a chance if you do, because more often prices go up than down. That said, a temporary dip in prices does happen more than I presumed it would, so the alerts can be quite useful.
Upvote:3
This is purely from a sample size of one but I signed up to Google flight alerts 87 days ago for flights between Manchester (UK) and various airports in the Alps. It seems that for in this case, the price of the route has fluctuated, with a general increase. I can say I haven't received any additional spam from Google, and they already had my email address for other purposes anyway.
It should though be noted that any of these services will only show a change in prices after they have happened. If you receive one saying the price has gone up, it's too late. And you'll have to guess weather or not it will continue to go up, or go back down again.