I'm working on working out an hourly rate also with plastic parts-production I do from other people. $65-75/hour looks to be right where I need to be to be profitable going forward. I do alot of custom doorhangers and wooden signs which don't pay as good but I try to do them in batches to spread the cost over several items.
My time is very valuable to me and my family. I do the Bot thing part-time and work as a healthcare professional full-time so I don't want to work all day and them come home and end up working 3-4 hours for $8/hour. It ain't worth it to me for that.