Oh man, if you have a Lego store anywhere near you then you are in for a treat! Every store I've been to has a literal tower of bins that are filled to the top with Lego mini fig parts. You can custom build you're own mini figs exactly as you want with one caveat: They may not have the EXACT piece that you are looking for but coming up with your character with some limitations is half the fun.

My personal favorite that I have created is Minifig Richard Hammond:

If you are artistically inclined at all you could look into Titancraft, Hero Forge, or Eldritch Foundry. They have online custom miniature creators, some will print them for, and some will even paint them for you.