On average, installation will cost around $450.00 for an in-ground system if you have it professionally installed. This includes two trips, labor and materials. Roof and wall mounted basketball systems will cost less because there are no material costs and assembly can be done in only one trip (no concrete).
There are several things that can increase the cost of installation including jackhammering into exisiting concrete, disposing of your old system, cost of concrete, location etc. Be sure to let the installer know everything you want done so he can give you an accurate quote.
If you will be doing the installation yourself, the only cost will be materials. If you're installing an in-ground hoop, the only materials you will need to buy is concrete. Check the installation instructions for for the amount of concrete you'll need. If you want to estimate on the high side, you can budget in $75.00. If you're installing a roof or wall mount, you will not need to worry about concrete. Tools you will need include post hole diggers, shovel, two adjustable wrenches and level.