Man...lots of discouragement here...

I've done it a few times. It's nice to have an extra set of hands the first time because sometimes you need some help pushing down the hub to give yourself room, and having someone thread on a nut under the hood when you re-install the spring/shock assembly.

As far as tools go, sure air tools make it easier but aren't necessary. You will need:

Spring compressor
Hand tools (socket set, open end wrenches, allen wrenches - all metric)
Torque wrench
Floor jack with adequate lift (not stock scissor jack)
It also helps to have a second jack to raise the knuckle when re-installing

Search for some DIY write ups, or better yet buy a Helms manual and it'll tell you everything you need to know about your car...more than you'll ever need, very thorough. www.helminc.com

It'll be a good experience and you'll learn a lot about your car. Take your time and be thorough, might take you a whole afternoon to do it.

To pay to have it done...it'll depend where you are at, etc...but expect to pay $100-200.

Plan on having an alignment done afterwards.

Read up on general safety guidelines for compressing springs.