Sorry not on here all the time to reply quickly, my personal opinion is....
We all know something is worth what someone is willing to pay and selling can be a tricky thing, I realise your at 38K miles but micky is heading towards 100k with a similar engine.
All the F owners know how sweet and smooth this engine is for performance and economy.
Depending on the condition, assuming stunning (good - fair) not broken or bashed, I would stab at more than 3k but less than 4k on the dealers forcourt who knows what

a in the middle stab would be £3,499 & 99p
smythson is right you just do not see them for 2.5k Samsgs knows this from his searches

even F650 singles are advertised for more than 2.5K
But other than Bike trader, MCN, fleebay, gumtree and the like there is the better and best place,
the for sale section here It's amazeballs I think more read through it than we realise, being the place where you can get lots of pictures honest facts, pm's are pinged around and often a deal is struck with secure money. If your going to give away a bargain
But for this there is a
£12.00 fee, which is small beans for the fantastic deals, here I might suggest starting at a less of a figure you know special tosser rates and if I had to go under three big ones it would be £2,999 & 99p
In the for sale section with lots of pictures is a good time of the year for sales, dont forget spring has sprung,
the grass has ris, It's where all the start of season bike buyers is. (& before mentioned humpers

)
It's interestin to me as I ride the very same, still on my F650 (but I need to get out more

a euro tripo is in the wind) I have added so much personalising it for my needs and tastes, more than 3.5k it does all that I want and more

But if I Had to sell it and had no bike for a period then went looking for another, it would be a 12

(and I would start in the for sale section here)
If the superior for sale and wanted section failed to sell then the above mentioned non ukgser inferior ones
One day
what ever you do all the best