I have yet to hear of a TR valve failing, other than burning from old age which is not a quality issue. I bet the prices are more a reflection of the supply chains for the different stores. Case in point:
We needed a new water pump pulley for our Range Rover. It is a 2004 with the BMW engine. I went to the Land Rover dealer and he wanted $1300. I then went down the street to the BMW dealer and bought the exact same pulley, exact same part number, for $36. I fully believe the valves you are looking at are likely manufactured by the same company.
Now, the big difference in valves is the stem diameter. The early valves used a thinner stem, and it was later increased to 3/8". Just make sure , as Hamish pointed out, that you buy guides to match the valves. You can also buy valves with larger tulips for a slight performance edge. Avoid those for your street motor. They also slightly reduce the life of the head.
There is a good chance you will need exhaust seats. The heat tends to cause the cast iron to wear, so the exhaust valves recess into the combustion chamber. Hardened seats bring them back up and will prevent them from ever receding again. In severe cases, the intakes can also recess, but that is less common.