Unfortunately its not as simple as that.
Hard wired. wireless and your budget has a lot to do with what options you have available?
Along with a proper assessment to work out what you should have.
The Main players are what I would stick with, so avoid anything you get at
Wickes and B&Q.
The bare minimum, you need
1. panel with a keypad
2. pir
3. door contact
4. bellbox
There are lots of manufactures out there, all of which will probably not support you doing a diy installation, so if you get stuck you need places like this forum to help.
Stick with one brand through out, it will make it easier for you.
Each manufacturer has a budget range and a premium range for the want of better words, and not everything that works on the premium range will work on the budget range.
A Texecom 12W live might be a good start, built in keypad, wireless devices and wireless bell box's but your limited to 8 wireless devices and 4 hard wired ones out of the box so to speak.