have 1907 bayonet need to know what it is worth?

These are sold on eBay quite regularly. I have two examples myself, both in fairly poor condition. If yours is in excellent condition (no rust, all original marks intact) and it is a "D.P." version (Drill Purpose - this will be stamped several times on the hilt) then it is worth around 70 to 100 pounds. If it is the standard version, or rusted, with worn woodwork or leather, it will be worth practically nothing.