I personally always strongly recommend against buying gears & installation kits that you will be paying someone else to install. If a shop installs your parts, they will only warranty their labor, not the parts you provided. If anything goes wrong after the installation, and it does (happened after one of my two regearings), the shop will blame the parts you provided and tell you their installation was flawless. The gear supplier will likely blame the installer (who is normally at fault) so you may be left out in the cold as they point fingers at each other.
Ask the installer to give you a good price (discount) on all the gears and parts and have them provide everything. That way, their warranty will cover anything that happens and you'll get the problem taken care of grief-free. Even if you pay a few bucks more for the parts, the peace-of-mind you'll have is well worth those few extra dollars.