Often the decision on software is presented as a "build vs. buy" decision where you look for software that meets your needs and then buy it or you don't find software that meets your needs and then you have to build it from scratch.

There is another option that is increasingly attractive.  This is the "modify" option.  You can start with software that meets some of your needs or which has a useful basic architecture and then modify it to meet all of your needs.  This option is difficult with commercial proprietary software which requires that the vendor be agreeable to make the changes. (Often local vendors are not skilled or not permitted to make changes.)  However, with open source software, you have access to the underlying instructions "source code" to the software so it becomes a much more feasible project to make the changes yourself or to hire someone to make the changes. 

Another advantage of this option is that the investment you make in changes to the software accrue to the benefit of you and others who use the software, rather than being locked up in a proprietary system