As a longtime tinkerer/bodger/shadetree mechanic, I've found a few inexpensive things that you might not necessarily think of as tools that can make life a lot easier around the shop.
1. Wire hangers. If you know somebody who gets their clothing dry-cleaned, they're free. They're malleable but strong, making them very useful for fishing wires through holes, copying contours from one surface to another, and using as prototype brackets (or, for us rat-bike guys, permanent brackets). You can also use them to hang parts off of racks (or trees) for easier painting
2. Dental picks. Usually found at flea-markets, they hold a very fine point, making them useful for pulling up O-rings, scraping crud out of small or awkward spaces, retrieving parts out of small or awkward spaces, etc. Just be warned- they can be very sharp, and they are also brittle, making them very easy to snap when trying to pry things.
3. Turkey baster. Generally available at dollar stores in the U.S., they're a great way to empty out master cylinders, remove excess oil from forks to fine-tune the level, and get oil into CX/GL cylinders without having it drain out the hole at the bottom of the spark plug tube.
4. Jumper wires. If you do any kind of electrical troubleshooting, you'll want to take the time to add a small alligator clip to each end of a meter or so of flexible 12- or 14-gauge wire. While you're at it, do two- one red (preferably with a 10-amp fuse in-line), one black. In particular, these make it easy to make temporary connections directly to the battery to bypass suspect switches and connectors and test replacement parts.
5. A few scraps of wood. A bit of 4x4 treated fencepost is very strong, and a couple scrap pieces, 6" to 12" in length, can often be just what you need to prop up an engine, block a tire, or support something you're pounding on. My jack of choice while stripping the Transverse Twin Armada out in the yard.
6. A box of toothpicks. Good for unclogging spray can nozzles, getting bolt holes lined up, removing goop from softer surfaces (aluminum, etc) that steel tools would tear up, getting wires routed into tight spots (inside handlebar switches, for example), removing bugs from teeth.
Weekend's a' comin', so get those tools ready...
...dave

