It's been a while since I purchased any amateur radio gear....
Last time I did:
Kenwood Amateur radio = free downloadable software. Must purchase programming cable.
Yaesu = programming software cost $, must purchase programming cable.
What else do you need?
Well, the radio will come with the mounting bracket, microphone, power cable.
You'll need to purchase an antenna mount. I'd -strongly- recommend a permanently installed NMO mount on your vehicle. Doing the install right from the beginning saves a lot of headaches. NMO is the de facto standard on the professional side and is popular on the amateur side. Going with a standard like an NMO makes it easy to change antennas as your needs/interests change. You'll want one with the PL-259 (aka UHF) connector to match your radio.
http://www.theantennafarm.com/catalog/larsen-nmokhfudpli-1867.html
$22.95
You'll need to purchase an antenna. NMO base, name brand, Larsen, ComTelCo, Laird, etc. There are a few dual band models available. Here's a good one:
http://www.theantennafarm.com/catalog/larsen-nmo2-70b-1712.html
$69.95
If your car is quiet inside and you don't drive with the windows down a lot, the stock speaker on the radio will be sufficient. If it's noisy, or you drive with the windows down a lot, I'd strongly recommend a good external speaker. They'll make for better sound, better intelligibility, etc. Well worth the investment, if you an fit it in your car, that is. Newer vehicles are pretty cramped, so it can be a challenge:
http://www.theantennafarm.com/catalog/vertex-mls-100-264.html
$44.95, but you can find suitable speakers much cheaper.
Installation of all this is another question. If you are comfortable working on your own car, basic electrical work, etc. there isn't any reason you can't do it yourself. If you are not comfortable with that sort of stuff, then it might be best to get help. Either a friend or a shop.
The antenna install will require a 3/4 inch hole drilled. There are specific hole saws for doing this.
The coax connector installation isn't an issue with the one I linked to, it's pre-installed, but it's a heck of a lot easier to route the cable without the connector installed. Installing your own takes some skill with a high wattage soldering iron.
The power cable routing requires routing from inside the car to the battery. This will mean passing through the firewall.
The power cable really needs to be connected to the battery, actually the + to the battery and the - to the body ground.
Installation of the radio means putting it somewhere that it's safe, and out of the way of airbag deployment. Physically attaching the radio to the dashboard, center console, etc. really is important since it can become a projectile in an accident.
Really nothing you can't do yourself, just depends on your comfort level, skill level, and if you have the right tools.