I am sure you can find something at a hardware place that you can adapt. They have a lot of inexpensive cloth utility belts that hold screws, nails, etc. - with a series of pockets. Tell them what you are looking for. You could attach a series of loops using wire, long twist ties, cable ties, or any other inexpensive holders. I assume you can then save money by using your real tools as accessories. Also look at craft stores - sometimes you can find something to hold other types of tools, and you can use that for the tool belt. If you are at all talented, you can probably find a pattern at a fabric store and create something out of a remnant of looped trim or even fake leather (like vinyl or "naugahyde"). It's going to be for nighttime trick or treating, so why not use a strip of black fabric (heavy duty) with some loops added to it, and hang the tools off it? Ask the fabric store staff - they are great resources for cheap solutions to things!
The tools "make" the costume anyway. Add a plastic hard hat and some plastic safety glasses. I've got a leftover set of plastic tools & hardhat but couldn't find a brand name. You could also try a "high end" toy store for those nature belts that hold a net, a set of tweezers, a magnifying glass, and so on - just repurpose it for Halloween. (If you're REALLY resourceful, put the belt away afterwards and give the nature set for Christmas or a birthday!)