I bought this plain black blazer from H&M and bought a couple hundred studs online from Etsy from this store:
The studs are very reasonably priced and there's a huge variety to choose from!
I bought some conical studs, some square studs, and some pyramid studs. The conical ones are my favorite! All you have to do is push the stud through the fabric and on the underside, press the two metal legs in. There's probably a tool you can use to make it less hard on your nails, but I was too excited to get started. It took me around 2 hours to get all the studs I wanted affixed. (I work slow though) But don't let the time, discourage you! This project is super easy and the end product looks great!
The total price of the studs was around $15 (shipping included from Thailand), so for a $20 plus the studs, I'd say this $35 jacket is good enough for me in comparison to the $3000 original!