Hey, I’m not trying to attack you here, just hear me out! I’m not saying you have to get rid of them just over that, I was just trying to remind you that if they’re straining your budget too much, it doesn’t make you a bad pet owner to give them to a another good home.
Because gerbils are burrowing animals, bedding depth is actually the #1 form of enrichment for them. I have 11 gerbils (5 pairs, 1 single), and they all have around 8-12" of bedding. They also have a big sand bath, a wheel, etc, but they definitely love the bedding the most!
But here’s the most important point: giving them more bedding is not as expensive as you think, because if you have a lot of bedding, you actually very rarely need to replace it! I’m not sure if you’re in the US, but if you are, I highly recommend this bedding! It’s only $23 for 85 liters, which should be enough to fill both cages with plenty of bedding, and possibly have some leftover depending on the cage size. After that, you only need to spot clean their potty corner, so bedding will only end up costing $10-$15 or so every month or every month!
I have depression too, and my gerbils are a huge source of support for me as well, so I totally get your attachment to them! You definitely don’t seem to be neglecting or abusing them, and it’s clear you love them, I’m just trying to give you a tip to make them as happy as they make you :)
EDIT: Also, before anyone asks, my single gerbil is only single because she is murderous to any other gerbil ever since her sister died, so sadly she is not compatible with a pair because she is the devil.