Old Mechanical Watch Service/Repair

[Haves1979]

On a bit of a whim I've just bought an old (1950's I think) Leonidas chronograph. The watch runs for over 24hrs easily, but is gaining a massive amount of time at around 2hrs over 24hrs. I've just had it looked at by my local watch maker and he's advised that it needs servicing and a new hair spring. He's quoted £150 if I can supply the hair spring, as I've no knowledge of this type of thing just wondering if this is reasonable? Just to add its a Landeron 248 movement and I think I can find a NOS hairspring from the US for about £40.