Enabling / Disabling Form Checkboxes Based On Value In A Cell

I have a sheet with around 3,000 rows of data. I need to be able to enable/disable different comibinations of three checkboxes based on the value of a cell in column D as follows:

If Band says £0k - £75k then all three check boxes should be disabled
If Band says £75k - £250k then the Step 1 check box should be enabled but the Step 2 and Step 3 check boxes should be disabled
If Band says £250k - £500k then the Step 1 and Step 2 check boxes should be enabled and the Step 3 check box should be disabled
If Band says £500k plus then all three check boxes should be enabled

When a checkbox is disabled I'd like it to appear visible but greyed out so it is obvious the option is not available, maybe via conditional formatting. I don't know if this can be achieved within any code rather than having to manually add conditional formatting afterwards?

I've attached a sample to demonstrate. Is this possible to achieve? I'm open to alternative approaches as well if this makes things easier to do. The mere idea of adding 9,000 plus check boxes if already scary!