It is possible to drive without the spin locks.
This should be only temporary as the back is not secured and will rattle at the rear.
I would buy the sellers spin-locks and install them, adjust everything nice before driving back. It can be tricky installing them and the right assortment of tools is needed. No special tools are needed. There are good write-ups on the installation.
A nice top, the correct color both outside and inside installed with spin locks is worth $1500 easy. Remember, the factory paint will match perfectly, both in color, depth and sheen.
http://mulone.com/hwm/porsche/