I'm glad someone finally asked a Question about alternatives to these jigs.
In the US at least, and probably in other parts of the world by now, pocket holes have become synonymous with Kreg. While they make good products that work exactly the way you'd hope, they can be expensive and their dominance of the market has led to a pervading belief among new woodworkers that the only way to do pocket holes is with a commercial jig when in fact pocket-screw joinery pre-dates the foundation of the Kreg company by several centuries.
Yes centuries, this isn't a new method at all. It's just that the technique was used very selectively back when joinery was all made by hand.
The simplest way to do this is probably the historical way, using only one gouge and a drill, in some cases fitted with only a single bit. There can be no jigging involved, just careful judgement of the correct screwing angle. Of course a bevel gauge can be used to help reference the angle or if preferred, a very basic jig (e.g. a wedge of wood) can be fashioned to ensure consistent results.
A little more about the history and alternative methods here:
Pocket Screws with Fine Furniture by Glen D. Huey on Popular Woodworking.
These days the simplest non-jigged method is probably to use just a drill, sometimes using multiple bits to form the various holes needed — a face hole (using a Forstner or sawtooth bit), the clearance hole in the first piece (this goes into the side of the hole formed by the Forstner) and the pilot hole in the adjacent piece.
No-Jig Pocket Holes on Lumberjocks.
Pocket-Hole Joinery on WoodMagazine.
Building your own jig
Of course if you want to do this with a jig then one can be made and there are a few types.
Building a jig for this can be a very simple operation, requiring no more than a few minutes of work if you're fast (but take as long as you need to make it right). Here's one of the simplest types, originally published as a reader's tip on Fine Woodworking:
DIY Pocket Hole Jig on Instructables.
DIY Pocket Hole Jig from CrazyRussianWoodShop on YouTube.
Pocket Hole Jig Plans on BobsPlans.com (with free PDF download).
Metal inserts (bushings) can be glued in place to extend the life of any wooden drilling jig, but even without those you can expect a lot of use before wear makes a jig such as this inaccurate enough that you have to discard it, even if made from pine or another soft wood. If made from a strong hardwood like oak or maple I think you can realistically expect it to last for a few years of regular use if you're careful.
I would fit metal inserts if you'll be using your jig very frequently, or alternatively make yourself three or four of the all-wood type in one go so that as soon as one wears out you can throw it away and immediately swap in a replacement.
Also see some related previous Q&As:
When are pocket holes an appropriate joinery technique?
What alternatives are there for pocket screws?