A business start up model that meets most if not all of your criteria is the trend in what I call "Permission Based Marketing". Permission based marketing essentially is getting people to opt in to a test-message marketing campaign (by scanning a QR code and being sent to a mobile opt in form; by texting a keyword to a long-code or short-code, depending on the type of mobile marketing platform one is using; by joining a local businesses VIP club in order to get discounts or other promotions; by accepting a mobile coupon onto one's smartphone...there are any variety of ways to use a mobile marketing platform for list building). Businesses that build opt in lists of their customers mobile phone numbers then have permission to send regular marketing messages. Those messages get read at the rate of 90+%, usually within 15 minutes, and have response rate that can get as high as 25-35% depending on the quality of the list and the quality of the offers. That can make a real difference in revenue for a local business.
The business aspect would be becoming a local mobile marketing consultant. You would need to have access to an sms delivery platform so that you could set up campaigns for local businesses to start. There would be some cost involved depending on your provider. Most local business people are more aware of text-message marketing but do not know how to get started or how to run an effective campaign. Effectively run campaigns can help develop leads for businesses; they can help the business acquire new customers; they can be set up to reward existing customers so that they come back more often and spend more money in the business; they can be used as appointment reminder services, which can increase revenues by cutting down on appointment no-shows. Again, what can be done with text-message marketing depends on the features built in to the delivery platform.
It is difficult to think of a business model that does not need clients or customers. So you will need to develop some skill sets, if only being personable. Learning how to be a local consultant is relatively easy. You do not need an inventory; it is a trending business with a high demand: in fact, industry studies are predicting that up to 80% of all small businesses will be using some form of permission based marketing by the end of 2013, if for no other reason than they will be getting left behind if they do not.
An offshoot of this is developing mobile websites for local businesses who have websites but that are not mobile optimized. Google keeps track of things because it is in the information business. Google's studies show that over 40% of internet searches for local businesses are being conducted on mobile devices. Almost everyone has a mobile device that can access the internet. Google says that 61% of people who search locally from a mobile device will leave a site immediately if it is not mobile friendly and go to a competitor's site. People who search locally on a mobile device are significantly more likely to physically go to a business they found while surfing locally and significantly more likely to buy something there than people who search from their computers. Facebook validates these findings because they report that more than 50% of their users are accessing Facebook from a mobile device. Getting the chance to educate local business people to these facts helps create a fear of loss that motivates them to act. That means business for the consultant.
Local business people need help in this respect and, if a consultant is prudent and approaches only local businesses that already are demonstrating a willingness to spend money advertising locally, the consultant will find enough of them willing to become customers and willing to pay for services rendered. Those services mostly involve the consultant's time, knowledge and experience running DFY (done for you) text-message marketing campaigns. If done correctly sms campaigns done for a local business person provide something that his current spending on advertising does not: the ability to track results objectively. Often times a consultant can show a business person already spending advertising dollars that he can divert something of that spending that produces no measurable results (print media ads for instance) into a well run sms campaign that can be tracked and produce relatively quick results.
One can become a local mobile marketing (mobile website) consultant with almost no capital. If you are interested in learning more, contact me by email. (This is my first post here and I am not sure if my profile allows anyone to email directly, but, if not, simply reply and I'm sure we can figure out a way to communicate).