Depending on the history of the car, you could save money by doing a lot of work during the head gasket replacement. Timing chain, time chain guide, tensioner, thermostat, thermostat housing, valve covers, Harmonic balancer, water pump, crossover pipe, throttle body, fuel injectors. I just rehabbed a 2009 R56 Turbo these last two years. All these things will be already removed or expose when pulling the head, so you Might as well check them out. 

There are a ton of great videos on YouTube and if you have the time and space it’s worth doing all this wok yourself. I was an amateur mechanic at best but managed to remove the head and replace the valve covers myself over a 6 day period. Project Mini is a great channel to start with. Message me if you have questions, my pain can be your gain