A gravel bike, unless you want something specific, is a great place to save some $$
Yes and no to that.
Yes - you are right that going the Aluminum route will save some dollars, and the AL frames also tend to have lower-end componentry on them so their are even further savings. If going with absolutely less dollars is your goal or you have a hard cap, then I’ll not argue against that.
However, here’s the counter-points: 1) Often for many people this becomes the bike they most like to ride, and will ride most often - even for triathletes. 2) These bikes if they are spending a good portion of time off-pavement and on gravel/dirt/trails are going to be subject to more of a beating and wear and tear. Here there is a case to be made for more durable componentry - and as you move up through the suppliers componentry lines, it tends to get more durable!
I’m in the market for a True All Rounder. It will be my ONLY bike (don’t do triathlon any more). I will most likely have two wheel sets - one for road and one for more dedicated gravel use. I know there was all kinds of debate about disc brakes a few years ago, but in reality the BIGGEST plus, for disc brakes is this ability to swap in and out quickly wheel sets like this for different usages.