I think when you weigh up the costs of a CLA/service you need to think long term. Most older TLR's will need one sooner or later, once slow shutter speed become inconsistent, sluggish and sticky it's an inication that the rest of the camera needs looking at.
Prices of cameras like this and its competitors are all over the place, yes you can get good bargains but often cameras you buy will need some attention.
My guess in this case is a simple CLA of the shutter would give you a good camera well worth the cost, the quote is for a complete CLA of the camera which is much more. UK servicing is much more expensive than the US and I could get that camera fixed for about $80 here, US price should be more like $50.