Though the benefit of open source is if you only need some of the connectors you should be able to save on the ones you don't need.

This seems to be targeted at specific people though, who have many of these systems themselves or will be backing up saves as a service for others. For instance I really only need my GB/C/A dumper. An NES dumper would be neat but if I needed that bad it I'd have it, they're probably $40 last I checked. If you need more than 3 of these systems though the $150 kit would likely save you money.