i wouldnt advise that you invest your money into such a business. Car computers just like like htpc's are not turn key systems. Paying customers are not going to care to fix bugs, updates and the like and they will come to you time and time again, killing your profit margin. It sounds great in theory, but will fall apart when put into a real world model. Your best bet to success in the field is to stick to turn key setups and do custom work based off that.