Sephora will color-match you for free. When you go into the store, just tell them that you want to purchase the HD foundation but don’t know what color you need. They will do a color-match along your jawline to find the perfect color match for your skin tone.
At the store close to me, when Sephora charges $50 to do a makeover they turn around and let you purchase $50 in makeup products in return. Did they tell you about that? Maybe you should call that specific store back and see if that’s the case. If it is, then you can use the $50 that went into the makeover to purchase the foundation and the other items you wanted to purchase.