I know they are not a particularly expensive item, but if you can do it yourself, why not? You can probably pay up to £30 for a hand forged chip carving knife; probably average price for mass produced knives is £10.
These old butter knives (good quality Sheffield steel blades) cost me £1 for the bunch from a charity shop. I ground them slowly, weting them regularly so that they didn't blue and the results were pretty good. they hold an edge well and chip carve quite nicely - evidence being the ornamental birch spoon in my previous blog. You can really only use one chip carving knife at a time so the question is, what am I going to do with the others?