Need a whole bunch of NeoPixels? How about a sheet of 20 you can snap off when you need them?
Designed specifically for wearables, these updated Flora NeoPixels have ultra-cool technology: these ultra-bright LEDs have a constant-current driver cooked right into the LED package!
In theory, the Flora can drive up to 500 pixels at 30 FPS (it will run out of RAM after that). However, after about 10 pixels (or if the distance between pixels is more than an inch or two) the resistance of the thread can affect the power supply. For large quantities of pixels over 10, you may want to consider using stranded core wire or copper braid to provide a "power bus" for the pixels - the current draw will add up fast!
Check out Adafruits Uberguide to all things NeoPixel!