My '13GT with BBP didn't come with a spare either.
Using Craigslist, searching "Brembo", I found a guy an hour away who had just sold his '12 GT that had the BBP.
1) 4 18" wheels and tires, with TPMS
2) A 5th 18" wheel with a new tire along with jack and handle
3) Roush Cold Air Kit
All for $800.
I put the 18s on for cold weather use during the months of November to April. Put the OEM 19s for the rest of the year.
To me, it is worth the investment of a full size spare for the peace of mind.