Some common kinds of jigs are available for sale at woodworking stores and even big-box retailers. Every time I see a jig for sale I think, “I could make that.” I imagine most of us think that! If I see a jig for sale that seems like something I could make, I try to be realistic about whether it is worth the time and effort.
I’m a cheapskate, and I almost always build jigs out of scrap, so the expense to build is very low. If you enjoy building jigs, then even if it takes an hour or two away from a paying job, at least it makes for a nice change of pace. If a jig is just a plastic version of something you would make out of wood, then you should seriously consider just making it yourself.
On the other hand, there are some jigs for sale that would be really hard to match with a shop-made jig. Sometimes it really is worth it to just lay out the cash and buy a quality jig. If you could build something “close” but would have to leave out some features or capabilities, then you should seriously consider saving up and buying the jig.
There is a third option that falls into this category: paying someone to make a jig for you. There are limitless operations you can perform with your tools, but there aren’t jigs on the market for all of those operations. You may require a level of precision from your jig that you can’t produce, or it may need to be made from materials you don’t have the ability to work. Having a jig built for you would be the most expensive of your options, but it is something to consider as a last resort. This may be a good time to make friends in other industries! I recently had a jig made for my shop, and I kept my costs down by trading labor with a friend who works with metal and plastics.