I had enough oil tossed in by the dealer when I bought the car to do an intermediate change. The BMW oil here was quoted to me in the $7 range.
If I were in your shoes, I would change only the oil @ 6 months with Mobil 1 0-40 from Walmart. I was going to do an intermediate change back in November, but had to take it to the shop for collision repair. Since the key read didn't show the May oil change, they changed my oil for free. If I can't swing the "annual" oil change in May, I will use the BMW free oil and then move to the Mobil 1 plan in future years.