Mr. E. Blackadder;
While I agree that the Crawford staff isn't much, especially considering the price, and also granting that the 20 inch or so blowgun wouldn't be really useful (you need a minimum of 3 feet), the idea of a staff and blowgun together is intriguing.
If one had access to the proper tools and materials, one could make a truly useful tool/weapon. Get a hardwood dowel about 1.25 inches in diameter, and 61 or so inches long (a good length for the indiviual). Hollow out the bottom 11 inches, leaving an outside wall thickness of 1/4 inch. On the other end, bore out a conical hole, much like a funnel, with 1/2 inch walls at the top, and tapering down to .40. Cut the dowel in half on a table saw. Use a router to cut a channel, between the hollowed out sections, to house a .40 blowgun. Insert the alumiminium tube of the blowgun, and glue the two halves back together. The funnel end is the blowgun's mouthpiece, and the hollowed out section on the other end is for dart storage. To strengthen the dart storage area, mill a brass or copper sleeve to fit snugly over the bottom of the staff. Weld on a plate to the bottom. Slip fit the tube on, and drill two small holes to insert a pair of screws to hold the tube to the bottom of the staff. When you need to use the blowgun, take the brass tube off (which then becomes a quiver; insert a string into the screw holes to allow you to carry it over your shoulder), shake out the 6-8 broadhead hunting darts (11 inch OAL), plus one in the blowgun itself. You have a fine staff for hiking, and a good means of food procurement, all in one. The hunting darts are easy to make, and effective on game up to rabbit size, without poison.