Not a direct answer to your question but thought I'd add that if you can find a screw of suitable overall form
but it's unfortunately not self-tapping
you can modify them so that they are.
Any screw can be modified to make it self-tapping, and the process is surprisingly easy.
All that's required is to create clearance and effectively a cutting edge, or more than one, and the existing threading takes care of the rest (just as it does on manufactured self-tapping screws).
This sounds like a lot of work but
it can be a very quick operation, literally a few seconds per screw at fastest.
So I'll concentrate on the fast-and-dirty method instead of those that create a groove similar to that seen on many commercial types.
Grip your screw in gloved fingers or pliers (pad jaws to prevent crushing the threads) and hold it against a grinder or belt sander to create one flat face on it, approximately 1/3 of the way up the threads.
Ideally it should retain its original point, looking something like this when you're done: Bingo, your screw has just become self-tapping.
woodworking.stackexchange.com/users/243/Graphus
The important parts are to have self-tapping screws (unless you want to do a little predrilling before using the screws, not recommended) and having a flat surface on the bottom of the head.
Depending on what you expect it to need to bear, most screws would handle this fairly well.
However, the Kreg pocket hole screws are HARD.
Your average deck screw is very soft in comparison.
I accidentally hit one with my biscuit joiner and totaled the blade.
It also made a terrible racket and barely touched the screw.
So that would be the biggest difference between them and some other screw you would likely use that looks similar.
woodworking.stackexchange.com/users/27/bowlturner
From what I can see of the pocket screws and their intended purpose you can find similar properties in screws that have pan or truss like heads.
Basically a wide head with a flat bottom.
You can also get screws with washer heads.
I ended getting screws advertised as Particle Board screws.
They had a washer head and looked similar to this.
The ones I purchased were threaded all the way unlike typical pocket screws.
It is also important to use self tapping / type-17 screws.
Like Doresoom points out:
It's a huge pain to drill a pilot hole at the same angle
I would still be curious to know of any other ideas people have.
I suppose you could also just purchase washers which you could partner with other screws but that would be a costly venture.
woodworking.stackexchange.com/users/128/Matt
I've made several rough projects where, just for practice, I used pocket screws, including a couple sawhorses, a little outside bench for taking off shoes, and my own workbench.
Each time, I actually just used regular drywall screws instead of the Kreg screws, for convenience and (a very little bit of) money saving -- not because they're at all the right screws.
One thing I really had to do with the drywall screws that I wouldn't have had to do with the right screws was to pull the joint very tightly together before screwing.
This is because the pressure on the screw to start tapping wants to push the joint apart -- even with a real Kreg screw.
But then, the threads of a drywall screw run all the way to the head, so the threads near the head grab the first board, and don't let it pull snug against the second board.
This is why Kreg screws have the partially unthreaded shank; that unthreaded part slips right through the first board, so the joint pulls snug.
In summary, for a rough project like your workbench, you can use any screw that fits if you're willing to clamp the joint very tightly before screwing.
And while the self-tapping feature and wide washer on Kreg screws are very nice features, the one feature I would really look for if I couldn't find Kreg screws is that partially unthreaded shank.
woodworking.stackexchange.com/users/1863/Mike
I know this is an old question, but I recently had to solve this problem myself, so maybe I can help someone who finds this later.
I used the SPAX screws, 1-1/4" Long for 3/4" stock.
They are REAR PANEL screws, and they have a 3/8" head.
$3 for a box of 30, and it took me about 15 mins to modify them all.
Not great time-wise, but batching them out helps, and it works in a pinch.
I modified them in two stages:
First took them to the bench grinder and ground a flat in the first couple threads as mentioned here: *
Then I chucked them in my mini lathe (but probably would have been faster chucking them in a drill), and ran them against a rotary tool with a mounted grinding wheel of larger diameter then the screw head (3/4" in my case) and ground the first few threads off to make the clearance on the shaft.
woodworking.stackexchange.com/users/7463/KW Daily
So I borrowed a Kreg jig from a friend and was using some scrap 2x4's to work on the  Community Project: Lets build a workbench! . Unfortunately I came to an impasse. I went to 3 local hardware stores on none of them carried "pocket screws" when I asked for them by that name.   Sure I  can  order the genuine article from the Kreg website but I am more interested in what other hardware alternatives are there to pocket screws?
What alternatives are there for pocket screws?
woodworking.stackexchange.com
<screws><community-project>
woodworking.stackexchange.com/questions/1708
woodworking.stackexchange.com/users/128/Matt
With regard to pocket screws and their intended purpose, you can find similar properties in screws that have pan or truss like heads. You can also get screws with washer heads. The important parts are to have self-tapping screws (unless you want to do a little predrilling before using the screws, not recommended) and having a flat surface on the bottom of the head.   The important features to find are a self-tapping thread and a flat bottom to the screw head. Other screws with pan or truss heads may be suitable. Screws with washer heads are also available. Washers could be paired with other screws but may be more expensive.
The important features to find are a self-tapping thread and a flat bottom to the screw head. Other screws with pan or truss heads may be suitable. Screws with washer heads are also available. Washers could be paired with other screws but may be more expensive.