If you can make it worth while, plan A is a good starting point. When time constraints become even more tight, plan B would be the one to go with. It's hard to get the correct numbers game down before you make it public. I went through a lot myself, only to go back to my original assessment and advertise residential services "From $25".
Personally, in my area, where winter is 6-7 months of the year and the growing season can be shorter than 5 months, I only fertilize (dry only, no liquid as it's illegal in Ontario as of spring 2009) twice a year, once in the spring, and again in the fall. I don't advertise steps, programs or otherwise. I advertise it online for a month in the spring and a month in the fall. I charge by the hour, plus material used to keep it simple.
People that are truly interested in a spray on fertiziler/grub control will pay for it. I wouldn't advertise prices, I'd work on selling the business name, high colour flyers for instance delivered in potential high profit areas would be the best bet. I suppose I could say I'd treat it similar to advertising lawn care work. Great ads, clear and to the point in full colour with high res print. At least, that's how the larger lawn care companies advertise their services.
These guys are the volume player in Ontario: http://www.weedmancanada.com/services.html