Affordable Microcontroller Alternatives to Arduino for Controlling 6 RGB LED Strands

I am a high school senior and am in charge of controlling 6 strands of RGB individually addressable christmas lights for my schools marching band. I have code running that allows an arduino to control the lights however I want (https://github.com/Ging3y/lights). However, our band cannot afford 6 arduinos to run the lights. My question is what micro controller should I use instead. The code only needs one digital pin from the arduino, so using it is overkill. Is there a better and more efficient substitute?

18 f series will allow 3 pwm outputs with a bus expander you could then us an AND OR plane , x / y lattice In otherwords ( multplexing) same as you would with columns rows scenario

Little advanced for a school project to be honest with you this is possibly Uni late part of a first year early part second year assignment

Not as easy as you think