Percolating project

I want to knit a top for the Big Girl Knits KAL. I am trying to find a yarn that walks the tight rope of satisfying my budget without sacrificing too much quality.

My grandma had a coffee pot on her stove that when the water got hot would percolate up into the glass knob on top. I loved to watch it. I imagine now I have little balls of yarn percolating up into my brain when I warm up to a project. *sigh* but then I come smack dab up against the budget ceiling. frustrating.