£60 sounds cheap to me, and not having a service contract on something that can cause you a problem at silly oclock in the morning is just daft. Especially right now we are turning non-contract work away we far too busy dealing with customers that pay for us to be around
CPX didnt have any wireless detectors IIRC so they must be aftermarket with a receiver. The CPX has a built in Digi so is normally monitored. Strange combo monitored alarm with aftermarket wireless detectors.
As I said, I dont know the products that well, its unlikely the OP will find a decent brand with a non subscription ap. Though, I would not recommend a non subscription app either, the ones that were free were always going down and because they were not being charged for the manufacturers were in no hurry to fix them.
Not that you can buy as DIY but there are a few people that recommend Texecom or Pyronix, I dont know these products well enough to recommend them but on paper they are far superior to the DIY tat