The question is, what type of 3d printing service you want to offer.FDM is cheap and fast to produce, but a lot of companies or also home users are able to print such parts.Sintratec is offering SLS technology to a low budget. SLS has not that high print quality like SLA, but much higher than FDM. Also the prints are very durable and temperature resistant etc. Have a look on TPU and PA12 materials what they can make. Also with such a machine, mass production is not an option, but you can create movable parts in one print which can used as customized parts for end customers to high prices. Have a look on the Sintratec Kit. You need to assemble it first, but that's the reason for the cheap price for the high quality.