What is an energy source which is relatively expensive to set up, but has a low cost once it is in place?

this protocol describes a detailed procedure for intracellular flow cytometry staining.

i tried the eyeshadow trick you told me about and it worked so good i i did a yellow going into orange colors and it was bright and you could see it on my eyes

answer: 45

explanationyou have to add as well to be it could be