If the cabinetry is still in good working order then you may be able to sell them second hand on gumtree or even give them away if someone is willing to come and uninstall them. This will save the installer some work and also prevent it from entering landfill.
By getting custom made cabinets for your kitchen or bathroom you can get them designed to exactly fit the space you have to work within.
Many cabinet makers can supply a flat pack kitchen that can be DIY installed.