I get most of my steel including o1 and stainless from MSC supply and alpha knife supply. Those two tend to have everything I need and they have fast shipping. For handles I recommend Rob carper innovations, alpha knife supply, and a local hardwood store. Rob carper does great hybrids and other neat scales but he is quiet a bit more expensive. Alpha has a huge selection of g10 for a good price, and hardwood stores are great and super cheap. I was able to get six 4ft boards for 55 dollars, some of those woods were cocobola, wenge, and purple heart.
Hope that helps.