funny, I was actually thinking about restoration yesterday, while looking at japanese swords (and seeing so many either being sold as bare blades or with very poor fittings (or WW2 fittings, which I have no interest in)).
There are companies that will remake saya, rebuild handles, even reform habaki to your blade.
On top of that, as the japanese sword aesthetic is a bit different than others (it seems), if you were to get a sword to full polish, you could never put it back in its old saya for fear of scratching the blade. You'd either have to keep it in shirasaya or have a new saya made.
Begs the question on what we're really collecting
Personally, I want to find a sword that is 'good enough' without restoration, not just to avoid the cost, but because I really don't want to be looking at something that looks brand new - a little patina is nice.
my nickel.
j.