How much will it cost to get a new brake caliper for the front passenger side brake?

[Purrr]

We have an 03 Pontiac Grand AM. The front passenger tire kept squeeling, we thought it needed new brakes, coz it's almost 18 months since we last changed it.
He noticed that the rubber boot in the caliper is damaged and is leaking brake fluid.

So how much would it cost to get a new one installed?
Is this something he can do, or does it have to be done at a shop?
How much would it cost at a shop?
Can we buy the caliper ourselves and bring it to the shop?

Sorry for so many questions. Thanx in advance

[tronary]

If you go to auto zone they will sell you the parts and show you how to install them.