The “housing” is usually called oil pan. Unless it is broken, the mechanic doesn’t have to replace it but only needs to install a new gasket between oil pan and engine block. There are pros and cons of the reinforced plastic one (vs. metal one). An aftermarket oil pan “usually” costs $50 or less. $500 labor for an 1 hour job seems quite expensive (not sure if it is expensive because your car is a special case and needs additional works taking longer). I would be happy if the total cost is less than $300. If the leak is not severe(ex: <1 qt per month), you don’t need to repair it immediately. You may check the oil level and top it off periodically. Note that oil also can be consumed in engine (depending on the model, less sticky oil like 0w-20 is usually consumed more), and if oil level goes down, you need to check the consumption too.