replacing main board after water damage

water bottle in backpack broke and camera got soaked. Dried it out, worked o.k. for about 2 years but now it is focus hunting and won't shutter. Had it looked at by repair shop, said main board needed replacement. Wanted over $200., I only paid $300 for camera. Wondering if I can replace the main board without too much trouble and where I can get a board and approx. cost.