Head Gasket Replacement

The head gasket on my 99 neon (2.0 sohc) failed today. I initially thought it was a stuck closed thermostat as the car overheated (with heater blowing cold air) this morning about 4 miles down the road. I managed to limp it back home. After removing the radiator cap, light brown sludge oozed out wreaking of oil.
I purchased the car used 4 years ago with 28k on it. It now has 81k on it and this is the first problem I've had with the car. Can anyone provide a ballpark figure on how much it will cost to repair? I assume it would be a good time to get the timing belt (and perhaps water pump) replaced too? TIA.

I don`t know about the water pump but I had mine changed in my 99 DOHC plus belts and transmission completly flushed ( that was about 150 alone) another shop put dextron-3 instead of I think it`s supposed to be atf+4 anyways my bill was around 500 and that was at the dealership. Hope this helps you out best thing to do is just call around.