That's not bad, considering alarmtec.co.za with a quick shopping on a Texecom 412, LCD keypad, 4 x PIR's and 2x outdoors + software cable comes to around R10k
So they would still need to wire it up etc which is labor. Unless its a wireless system which its not because that would be pushing R40k lol.
Get 3 quotes, compare them. Also, if you don't mind a contract for 3 years ADT and others offer a "free" base alarm install and you pay for the extras but then you have to commit to a contract with them.
The people who owned this house before me were quite paranoid, they spent at least R130k with ADT - i've tried to work it out by adding up the parts on sites I can buy from...