The price is ‘ballpark’ but might not be fair, the posters above are showing prices for well regarded, well known tuning and service centres with a history of great customer service and documented history of putting things right on the rare occasions when things have gone wrong.
I’d ask who’s is going to do the work – it is someone ‘in house’ what’s their background, what is included in their ‘services’ change the oil and seals or is it a complete strip down and rebuild? If they discover a part has failed are they able to determine whether it’s wear and tear, accident damage or a manufacturing fault – personally whenever anything has gone wrong with any of my Fox stuff (that’s less than 2 years old) Loco and Mojo have asked Fox to replace it, lots of expensive parts on suspension stuff these days.
I suppose the point I’m making is that there’s a handful of well-known, well regarded Bike Suspension service centres in the UK, your LBS is probably subbing it out to one of them, but there’s also a lot of newer places who advertise on eBay and the like – given that there’s not a huge variation in prices and none of the things you want done are difficult to remove – I’d send the lot to TF or Loco.