Koho is also one of my favourite spoons, but costly as it is effective.
I have yet to find any blanks that are close to them in shape.
You might want to check out rvrfshr spoons made by a small company across the boarder.
They are slightly rounder oval spoons closer in shape to Little Cleos or BC Steel.
They come in 2/5 oz and 1/2 oz sizes suitable for steelheading and sell for around $20 per 10 pack or 2/3 the cost of BC Steel spoons.
You still have to add for shipping and handling so cost does go up in both cases.
I have used them and quality is good for the price and shape is very close to the Pen-Tac spoons.
I also pick up Little Cleo 2/3 oz spoons when they are occasionally on sale at Bass Proshops for I think around $2.75 per piece.
Action is slightly different from Kohos but only half the price.
When I fish non-snaggy runs, I still use mostly 3/8oz and 1/2 oz Kohos as I just don't get the same feel and confidence from using other spoons.
I also use 3/16 oz crocs a lot, and have not been able to find suitable substitute blanks for these either.
http://store.rvrfshr.com/product_p/rvrwaggler.htm