It is all down to condition. In less good condition it will cost less but once the repairs are made to high standards you will usually end up pretty close to the same prize.
In Finland it would be worth somewhere between 700 and 1200 euros in working condition I think. British secondhand prizes are generally a bit lower.
However it's practical value is very high compared to it's market value. If you take good care of your Whitehead and maintain and lubricate properly and shift bearings and do some repairs when needed it will still plane wood with perfect results 50 years after the last Axminster hobby or Jet machine was scrapped.
Even if you ended up paying a bit too much you have no reason to feel sorry. Just spread the loss over the remaining lifetime of you and your children and maybe also your grandchildren