i think my 12v sla was bout $40, and charger maybe 20, i run my deck off a cig lighter from a car on the sla, i just went to the local O'Reily's auto store, and bought a new one for replacement, soldered my contacts on, and plugged it in and works like a charm. if you need help with it, pm me, i'll send you some pics, or make it for ya if you want. let me know.
matt