try smart needle they have many colors also have free embroidery designs.
I use serger thread, it works perfectly and I have a good many colors. If I need to I use the same color embroidery thread.
Sulky has a new thread line out called Poly Lite and it works great for bobbins as well as embroidering small/tiny lettering. And it comes in quite a few colors. JoAnn Fabrics has had Sulky thread 40% recently. Hugs. Nan W
BFC-Stash sells 60 weight Bobbin thread in large cones and they have several colors to choose from.
See link below.
EastWitch2
Well, I go with the recommendation from Tavernmaker...they are experts in FSL items...they recommend using serger thread...I know...but it works like a dream...it comes in an abundance of colors and is very inexpensive...I would buy a good quality one to prevent excess lint...wind your own and match your colors perfectly...
I have tried rewound bobbins, just white ones, and my machine did not like them at all! I have a Babylock Ellageo, so now I just wind my own bobbins with the colors I need and use the tip given by someone here about using a golf tee to keep the bobbin with the spool it goes with and then wrap a mini hair band around the bobbin to keep it from unraveling - works great. I am partial to Madiera Poly Neon 40 thread and use it for everything - even FSL.
I've used both the bobbins I wind myself, and the pre wound kind. I'm using a Brother SE400 machine. It seems to like the pre wound bobbins better.
They have 34 colors in various sets of prewound bobbins at ABC
Most of the time I fill bobbins with the same thread I am using on top and if embroidering a really thick piece, just slow the machine down. Floriani carries 60 wt bobbins and I think they have a big sale going on right now.
I will check out the Floriani website. That's where I get my stabilizer anyway. Thanks!
When I do FSL I wind my own Bobbins with the same thread as I use for the top. If you want to use 60 weight and have more color choices You might want to purchase spools and wind your own.
Google "embroidery thread 60 wt" and you can find assortment of colors.
Here is one link