Help,
I was driving my Jeep grand cherokee laredo 99 when the needles on my gauges started moving back and forth eractically. Also my engine light and brake light came on.
The mechanic thinks it's the ignition module or computer I just dont want to get ripped off again :[

There is a very good chance the battery is weak or it has a bad ground. Sweeping gauges and briefly cutting out while driving are the common symptoms. Load test the battery and clean the battery terminals.

Did you say it cut out? if it is all just insturmentation I would look first at grounds and connections. If that isn't it, it may be a bad insturment cluster. There are usually one or two "radio" repair shops in bigger cities that can rebuild/repair electronic clusters.

what was the code for the check engine light? that can be very inportant. infact see it there are any non mil codes, like battery voltage low codes.
if the engine is cutting out or lights are dimming etc., it cant be just a cluster problem. it has to be an effect not a cause. if your battery voltage drops below 9.6 volts your car can do some pretty funny stuff. i would look at that first.
hopefully your tech is not one of those guys that start throwing modules at things then trubble shoot it later if it still has the problem. i have known guys like that.