Shot starter?

I installed headers went out for a drive, stopped to check oil and adjust timing a bit. Got back in turned the key and all I got was a click. My friend came with his toyota pickup to jump me. We had to let it sit for 3-5 minutes before there was just enough power to get it started.

This morning I took out my multi meter and the battery reads 12 volts. 12 volts at the big connector on the starter. engine is stone cold and it just clicks when I turn the key. Is there anything else I can test?

If it is the starter can I get one smaller? nothing too pricey though.