Here's a fresher (and MUCH MUCH cheaper) alternative to studs or spikes: Nuts and bolts.
With some nuts and bolts and a leather punch tool, you are good to go!
P.S. For this instructable, I spray painted the nuts and bolt gold.
Step 1: The Shoe
I guess you can 'stud' anything with the nuts and bolts, but I really needed kickass shoes, so I decided to zhuzh up my pair of brown leather shoes. This pair has a foldover flap detail, which makes it perfect for adornment. Plus there will be no concern with the screw heads being in direct contact with my feet. Doubt that's gonna be comfy.
Step 2: Measure and Mark
Measure out and mark the points where you want the studs, then punch out the holes accordingly.
Here, I cut a piece of canopy repair tape (or any thick-ish flexible material) to the size of the flap on the shoe to use as a template.
Step 3: Start Screwing
Once the holes are punched, start screwing!
Step 4: Mix and Match
After I was done with all the hex nuts, I thought the pattern needed more visual interest, so I added in square nuts.
Fierce shoes ready to kick ass! (Oh, I did spray paint the soles gold as well, just to tie everything in.)
So there you have it! Nuts and bolts instead of studs and spikes. Spray paint them with whatever finish you prefer, stud them on anything you want. Have fun!