Save time shopping around for all the components. And ... no leftovers hanging around! Kits include comprehensive instructions, needle and thread if applicable, and all the beads and/or findings needed. You may just need tools, and this will be listed in the item description, as well as sizing, level of difficulty etc.
Bead Shack kits have earned a great reputation over the past 10 years as being easy to understand, well organised and good value.