td5 exhaust valves

Suspect head gasket on td5 disco. Took head off and can see anything untowards, but going to get it skimmed and tested regardlass, before i put it all back. Some of the exhaust valves are pitted more than wout would come out with lapping. Just wondered new non gen exhaust valves are typically £3 each and genuine or oem are about £17each. Question is how good are these, has anyone used non gen valves and what do you reckon. Seats on head are all pretty good.Trying to do the whole job on a tight budget. Thanks in Advance.