I own a Hillsview alternate kitchen layout, and while I can't help you with the exact price I was quoted for quartz (because I don't 100% remember and because quartz for the alternate layout was about 4k), I do remember that Mattamy's price was very competitive, especially considering it includes the upgraded undermount sink and upgraded faucet. I also really preferred not having to deal with hassle of doing it afterwards.. worth a few bucks difference to me, if there was any.
Oh.. also I was told at the time that the 'premium colours' thing only applies to granite, but for some reason they don't list quartz and granite seperately in the booklet.