Not knowing anything about your city, so I'm guessing here, but I would assume that your local utility companies, department of transportation, department of natural resources/conservation, highway patrol, etc. pretty much anything that is at the state, county or corporate level, probably has already collected the data. Between all of them, at least one will have imagery at a resoution that you want. If there is any organization that you have a good relationship with, I would check with them. Depending on who you talk to, you may have a good chance at getting the data just by trading favors (tax maps for aerial imagery) or if you are working towards a common goal. Though I've seen it go the other way, where one utility (for example, electric) won't give up their data to the water company because the water company has a good relationship with their competition. And I've seen power struggles with data.
I would guess that if you're as helpful in your city/job as you are in this community that you'll have no problem gathering data from other local sources. Some may give it to you, some may charge you a bit. But it doesn't hurt to ask.