Battery in trunk kits?!

I decided to pull the 'Stangster outta the garage today and bring it for a drive to the supermarket. It started up fine, got me there, drove great... But when I came back out it wouldn't start. All I heard was the starter click, and nothing. Stereo worked, I was able to put my windows back up, put my 'vert top back up, stereo worked, etc...

I really think it's my positive and negative battery wires because every time I clean them and its the wires that need replacing.

Does anyone know who makes a good Battery in the trunk kit? The wires, the box/holder/everything I need?

Thanks!