(idiomatic,regional) a low, minuscule price (literally: an apple and an egg)
Er arbeitet für 'n Appel und 'n Ei.
He works for almost nothing.
Etymology
From German Low German and/or Central German; see Appel(“apple”). On farms, apples and eggs were often the most numerous produce, so they were very cheap. The same in Dutcheen appel en een ei.