I'm not a fan of eSun PLA. In my experince the filament tends get pretty brittle towards the last 25% of the roll and snap mid print. That usually happens with filament that has taken some moisture, but I live in Southern California, where humidity is pretty low, and this doesn't happen nearly as often with other brands I have used. I use dry box that keeps RH at ~10%, but I've still seen it happen, which makes me throw the roll into my heated driers for hours before it becomes useable (unusual since PLA isn't that hydroscopic). Maybe the packaging is worse, or they tend to send older stock compared to other companies, I'm not sure.
For budget filament, I've had good experiences with Polymaker and VoxelPLA. Polymaker uses cardboard spools, which might not play nice with an AMS unless you print a reinforcing ring. Both filament brands have extra additives in the filament, so they wont print exactly like a more pure PLA. The claim is that they will be easier to print with, however in my experience it does have an effect on the strength characteristics of functional parts. Polymaker in particular seems to be a bit weaker and have a slight matte finish (which does look nicer for presentation prints). VoxelPLA seems a bit tougher in comparison, although both are less stiff than a more pure PLA. Unfortunately there are no established standard for modified filaments (ex: what does PLA+ really mean?) so it's a bit of a guessing game unless a filament is reviewed with robust testing.
Some brands offer substantial discounts if you order in bulk. Eryone and ZYLtech comes to mind, where they sell packs of 10 rolls for $10-13 per roll, but I basically never need to consume 10s of kilos of filament in a super short time, so I've never tried this option.
I'm in the US, so prices might differ significantly depending on location. You might be able to find local suppliers that meet a good price/performance ratio.