If you think your tanto is worth it, then do it.
Even though you likely wont recoup costs involved, ive enjoyed bringing a tanto koshirae back to life.
Though would not use the set above, the kashira has certainly seen better days. You could keep costs down by using one made from horn, though that wouldnt match your fuchi with the decoration, in my humble opinion. If it were a more simple plain iron fitting, then yes.
You would need new fittings and saya plus ito. You can search around to keep costs down, keep things simple, look for fittings something that fits right. Saya should be original to a blade.
Luckily in the UK, we have good guys that do good work that have reasonable prices when it comes to jobs on koshirae.
Always something on the back burner that needs sorting out.
Though only if you think its worth it, if its sentimental to you then that's as good a reason as any.