depends on how you define driveable. JB weld might hold on the diff case for a little while. Used diffs are available for around $200-$250. It needs plugs and wires. With that, it'll be driveable. The top has a tear that would need to be professionally fixed. The rear window for the top costs about $25 to make and install yourself - instructions on miata.net.
Tires are good but it's just got ugly steel wheels. A/C is inop - don't know why, and it's missing a radio.
It is a 5 speed. 130K miles - only middle aged in Miata terms.
Hope that helps