I have had the exact same question this week, and same end results. Nothing but Philips and torx at hardware stores. Ordered from Blacksmithbolt, but only needed 4 - #6 x 1" screws so ended up ordering over $20 of various things to get over the extra $4.00 charge for small orders.
Now today I need 2 - #6 x 1.5" bolts 40 TPI for jaeger sling swivels. I widened the swivels slightly so the provided screws too short. Track has a bolt (it is for their brown Bess swivel I think), and only a couple dollars, but will be over $16 by the time shipped. I will look in town tomorrow, but imagine I will be ordering when I get home. If I could plan ahead at all I would save a bundle on shipping, just had an order of other stuff from Track last week and 2 more bolts would not have changed that shipping cost any.