I may be the only one that says this but I did not like Sylvia's Yellow cake recipe. I like a moist dense cake and I found this to be a bit on the dry side. I didn't over bake. I made 3 tiers and they all came out the same.
Do some price comparisons in your area(not from a grocery store bakery). Figure out what your costs are(time and $).Price points are different in different areas so it would be difficult to tell you exactly what to charge. HTH