It really depends on the functionality you are after.
I tend to go down the Add-Ons route. Most add-on will get you close and some will do customizations to get you the rest of the way but you definitely need to get that in the statement of work. If your var has the capacity to create an add-on, this is always an option but usually a more expensive option. Worst case scenario, would be to buy the SDK and create it yourself.