Re: Quality Difference: Standard vs Custom
You'll pay more for a custom sized window because they're made to order, more time and manpower involved, whereas standard fair from the big box are all cookie cutter. As for quality, that would depend on the type, brand, and model of window.
While you may pay more for a custom window, you'll save on installation costs. Yes, you can buy standard windows and reframe the openings to accommodate them, but then you've got additional materials and even more man hours involved in the retrofitting.
The only way to truly know the cost differential would be to price out standard windows with the additional installation/repair costs against custom windows that will be a direct fit. You also don't have to go with a custom window company to get custom sized windows, any big box can order them OR your contractor can probably source them more easily from other suppliers.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!