Another thought that occurred to me is Metro Embroidery thread (on line only), their prices are rock bottom so you can order a lot of threads without a lot outlay or order mini spools if you are unsure of the color. It is good inexpensive strong thread for charity work. Lots and lots of colors and dirt cheap but it is very shiny so if you don't like that lustrous look and prefer a matte finish or only use cotton this would not be a good option for you.
https://metroemb.com/store/index.php...ry&path=72_105
Another very affordable option is Connecting threads. I have run their thread though my LA. Not a huge fan of it but that is just me, others love it. I find it too linty and I much prefer the shiny look of the trilobal poly embroidery threads.