You don't have to buy these screws online, overseas, or from somebody else. All you need to do is go to your local hardware store (Home Depot, Lowes, ACE, literally any old store) and look for these screws.
Trigger Guard Screw: #10-32 x 1-5/8"
Rear screw: #10-32 x 1-1/4"
Front screw: #10-32 x 5/8"
Just some info if you're a newb on screws:
-Numbers before the "x" describe the threading. Numbers after the "x" describe the length of the shaft, in inches.
-The second number can be give or take 1/8 of an inch, but try not to deviate unless you have to. Fitting problems may occur if you do.
-The screws you are getting must be non-tapered (they aren't the pointy kind; may also be called a "bolt").
-Steel is Real, but Brass is good too. Avoid zinc alloy (aka pot metal) unless you have to. The better the material, the less worry you'll have.
-Lube your threads before inserting, or else you run the risk of stripping.
-Any labels like "Round Head Slotted", "Flat Head", "Countersunk Head", or simply just "Round", "Flat", "Countersunk" describe the shape of the head of the screw (the top part, opposite of the tip). Ideally, you want a "Fillister" head, and if not, a "Round Slotted" or simply "Round" head.
IMPORTANT: You MUST MUST MUST make sure the "head" of the screw/bolt isn't too fat. Otherwise, the heads won't fit in the cutout slots of the stock. If you can't find a screw with a small head, you can choose to either widen the cutout slots in the stock, or buy a "Countersunk" head in which the head will widen the slot itself, or buy longer screws so they can go over the cutout slots and still reach the threads.