Problem with Camaro 125,000 miles

I have a 2000 V6 3.8 Auto Camaro. Had the car since high school and she was brand new. Now she has 125,000 miles on her. :) Paint still looks great (silver). About six months ago she started over heating. Radiator and hoses were replaced. Also replaced the spark plugs and wires (never were replaced before). Took a trip to vegas and she died right after I got there. Had to U-haul it home to Phoenix. Had my auto mech. check her out and turned out to be another hose (this time metal) was leaking. Repair was made and he said the temp should not go over 210.
About a month later the car would overheat everytime about 5 miles down the road. I turned on the heater and this would bring the engine temp down to normal. I think it's a bad thermostate. The Oil pressure seemed to drop below the middle marker also. This was in December so not sure if the cold lead t the drop in oil pressure. Just never noticed it before.
I was going to replace the thermostate when all of a sudden the engine started making a banging noise. I think its a valve problem.

When this started to happen I went out and bought a new car (a 2008 350z with 4200 miles).

Question: How long are these engines designed to last? Is my Camaro worth fixing? How much would a valve fix cost if it is the problem? I think its the front left valve. My plan is to have the Camaro as a second car used only for city driving or when I need four seats. The 350Z would be a weekend/night car.

Thanks for the read, Mason

Sorry to hear that Mason. But as far as engine life, it should've lasted you over 200,xxx mi. At a fairly well mantained schedule. The overheating part was probably because your mechanic not bleeding the thermostat housing after he filled it with coolant and water. Honestly I don't think it would be a financially wise desicion to fix it because being a v6 the value of the car is not that great, what I'm saying is... you are better off buying another camaro and make one out of the two but you waste time and money or simply get another car. I got a 2000 firebird 3.8 and I'm almost at the 200,xxx mi mark and I'm confident the I ca still take it on a road trip with no problems.