It would depend on the vehicle.  Many do require shims or kits to make
adjustments.  In some cases because the car "from the factory" provides no means
to make an adjustment and the shop actually has to make modifications (change
parts, grind out bolt holes etc.) to the vehicle.  The latter is rare nowadays
though.

Even so, 100 bucks sounds high so if it's just a simple set of shims I would say
they are gouging you.  Find out what the "kit" consists of and post back with
the make/model.

Depending on the make and model of the vehicle:

The kit can consist of two bolts, with eccentric washers on them, and then
the technician might have to knock out metal plugs or grind out the
secondary metal plate. To make the kit functional.

Most alignment shops, just charge you $49.95 to $69.95 to do what is
referred to, in the alignment trade as:"A Toe And Go" where they only set
the toe-in, and leave the camber alone. (Camber is the angle that causes the
inside, or outsides of the tire to wear)

Just the fact that the shop told you need the kits, is a sign that they take
pride in their work, because most use the toe and go. Then blame the uneven
tire wear on other factors: i.e. shocks, sagging springs or a million other
crocks of sh.t.

If it's a Honda, the kits are even worse, they are the mounting point for
the upper wishbone (Control arm) and they are about $10.00 a piece,
wholesale.

Ask what kind of kit you are getting, if it's a shim, on some cars the labor
of fitting them can take up to two hours, so considering the price of the
shim around $8.00 for most. Most shops charge $58.00 per hour labor. Look at
the price that way when they break it down.

Get it itemized!

Refinish King