I had an RX-8 for 5 years. It didn't have a spare tire, nor did it have run-flats. Instead, they included an air compressor and a can of fix-a-flat goop in the trunk.
I never used the goop - instead, I learned how to plug tires. It's easy, google will show you how. Fix-a-flat will ruin the tire and annoy the tire shop guy that has to clean it up, plugs are permanent fixes. Through those years of ownership, I never had to plug a tire on the side of the road. In the couple of cases where I picked up a screw or nail, I could always use the air compressor to get enough air in to safely get home and fix the tire in my garage.
When my 135i went through it's first set of tires, I replaced them with non-run-flats, bought a BMW scissor jack, an air compressor and a AAA membership and still came out ahead over the cost of the run-flats. I never had to use any of that stuff in the 3 and a half years I drove with non-run-flats.
I'll be pulling the run-flats off my shiny new 328i soon and will store them for the lease return. I'll put the jack, the plug kit, and compressor in the trunk and make sure there's some kind of lug wrench in there. If not, I'll also carry my torque wrench. I still have the AAA membership. But my plan for a flat is pretty simple:
1) Low tire? Air it up, fix it at home, at a rest area, or at a tire shop (usually about $20 to plug a tire, some places will do it for free if you bought the tires there)
2) Blow out? Have AAA take it to a tire shop. I don't expect BMW roadside to help with a tire issue if I don't have run-flats