Support is a big thing as well for business software. When you buy "off the shelf" package from commercial vendor a large chunk of the cost is usually in suppor

Support is a big thing as well for business software. When you buy "off the shelf" package from commercial vendor a large chunk of the cost is usually in support contracts. If you have a bespoke system built from open source components it can be difficult to find people able to support it. I think there are pros and cons to both approaches. Sometimes it can be frustrating trying to shoehorn the vendor supplied peg into your business's particular hole. I've heard a lot of people over the years complain to my manager "XYZ is crap I could write a better solution using ABC" the reply is usually along the lines of "Yeah but are you willing to spent the next 10 years supporting it."