Unless you will be installing the gears yourself, which I won't do myself and don't usually recommend others do, don't buy the gears & master installation kits to give to the installing shop. Instead, have the installing shop provide ALL of the parts. That way, they will have to cover all parts & labor costs if anything goes wrong during the warranty period.
If anything went wrong during the install or during their normal warranty period. the shop would likely just blame the parts you provided for them to install. And things do go wrong with ring & pinion installations either during or shortly after they are installed... installations don't always go perfectly. If you provided the parts, many shops would just blame your parts & have you get them replaced by the parts dealer & have you pay the labor again since they likely just blamed the parts. And the parts dealer would likely blame the installer... who is normally at fault.
You don't want to be caught in the middle as the installing shop and parts provider point their fingers at each other.