My original tutorial for using Bics/Sharpies like Copics is HERE
I've been using Sharpies and Bics just like Copics and am happy with everything except the fact that they don't have pale colors. Since I wrote that tutorial, I've actually bought a few very pale Copics, with coupons at Hobby Lobby. They mix and match with the Bics and Sharpies, which I bought in the big packs with coupons at Target and Office Depot. It works, and it doesn't cost a fortune for decent color selection.
I just couldn't justify spending hundreds of dollars on a coloring medium because I don't color that much and this is just a hobby for me.