Aircon repair quote VS

[vsv8berlinawag]

I have been quoted $350 to replace a TX valve and a filter/accumulator on a VS 5 Litre. Does this sound reasonable ? The symptoms are basically that when it's above 35 or so degrees the a/c runs for approx 10 mins then gives up and blows hot air. They put their gauges on and they told me that there seems to be a blockage in the system (TX valve) as the gauges almost go off the scale when the a/c is running.