You set #of days from install date of part and a minimum $ amount, under Makes / Custom Properties Tab (to get there select the Inventory drop down and go to 'Makes', then select which Make you want to set and you will see the Custom Properties tab). ID90 Parts warranty alert will look at these parameters before triggering.
If a manufacturer says they will only cover parts for 90 days that costs more than $300 then you would go into that Make record, and make ZCJMakeWtyDays to "90", and ZCJMakeWtyMinCost to "300". Alert will fire when either/or Custom Prop condition is met.
NOTE the "ZCJMakeWtyMinCost" custom prop must set up as a numeric number. CEOJuice will normally set these custom properties up for you, if you choose to do it yourself ensure that is it set as 'numeric' value and not currency. Otherwise it will break the ID90 alert.
See here for an explanation on ID90 Parts Warranty process.
Keep in mind the logic for this alert assumes that if the manufacturer covers the machine as a unit then it would be covered PERIOD (as long as it is within the warranty date). If the machine is no longer covered as a unit then you fall back to parts level, where the manufacturer only covers certain parts with lots of conditions and that's where the price (ZCJMakeWtyMinCost) would come into consideration.
We understand this logic may not be true for every manufacturer which is why we're moving towards the model of a different version of this logic for each major manufacturer. Of course that is quite a bit of work so we haven't gotten it completely wrapped up just yet but it is on our radar for the reasons listed above.
You can also set ZCJMakeWtyDays at Item Level (Item Level Custom Property overrides Make Level if both exist):