SleepyHa

i bought an 02 grand cherokee "as is" about 2 weeks ago. when we first checked it out it was fine. a mech (inexperienced but still a mechanic) said it was fine and for the first 2 days i had absolutely no problems. then the heat died. then the next day.. my left turn signal stopped working.. then the next day it wouldnt start. turns out my battery was dead so i replaced it with a new one. it started right up. the next day i turned my headlights on and the dash went dim. the next day i turned on a wiper and the radio turned off. last night i got in the car and noticed that the dome lights didnt come on. who knows what's going to be wrong with it when i leave work today.

i'm going to take it to my real mechanic on saturday but i'd like to have some idea of what's going on before i take it in.

any ideas???
even better question.. any ideas on how much it's gonna cost to fix?