You might check local listings for "fasteners"
The sort of place that sells Grade 8 bolts and nuts and aircraft fasteners and such.
If you check MSC or E-bay or Amazon you might just find a box of 100 for a price low enough to not worry about the 99 spares.
I'd think,it would be under $5
Often buying a box of 100 of just about any small hardware (stainless screws and nuts,tee-nuts,etc) delivered to your door beats driving around paying $3 for a baggie of six.
Beware your eyeball might not see the subtle size difference between an inch and a metric size.
One more thing. Suppose you took a 1/4-20 allen head cap screw (or similar)
and ground the tip of the threaded end back 1/32nd of an inch or so.,as square as you can. That will get you nder the surface hardening ona cap screw.
Then take a drill bit just big enough your pin will slip easy into the hole,and drill into the end you just ground off maybe 1/3 the length of your pin. Or 1/2...it don't matter much.Its even OK if its off center. You do want the hole in line with the length of the screw. Obviously,a lathe will work.If your drill press vise has a vertical vee groove,great! OK,you can use a hand drill.Its just a screw.
The plan is making a roll pin starter punch that will hold your pin square and straight to the pin hole in your gun so you can get it started.
You can taper or shape the outside of the end of the screw/punch or drill the hole offset as you need to get the pin to the hole. Like,don't ding your slide.
I just don't do trying to hold a roll pin with fingers,tweezers,hemostats,etc any more.
Drill you a starter punch.