If you struggle to earn funds you could always try and sell "fan made" City merchandise.
Thats how a lot of groups generate their regular income in Germany.
The majority of fans at my own club rarely buy official merchandise as it is expensive and looks crap as well. Most of the stuff done by the Ultras or similar groups looks better, is cheaper and has a better quality as well. I think the only official merchandise I have is a scarf, but other than that....
The whole thing is pretty big in Frankfurt and one of the guys doing this got his own shop since years in one of the biggest shopping areas downtown.
Here you can see what the "inofficial" merchandise can look like: <a class="postlink" href="http://www.fanhouse-frankfurt.de/" onclick="window.open(this.href);return false;">http://www.fanhouse-frankfurt.de/</a>
As someone mentioned already the "Charming man" would for sure sell like mad.
Get it printed on a blue T-Shirt, have something like the 1894 logo on it as well and sell it on match days.
Its relatively cheap to make and if you sell it with something like a 5$ gain you will have a nice income and I am pretty sure there is a huge demand for it, seeing the reactions towards the banner.
Just need to make sure that you don´t use the official club logo as this might get you into trouble with City (unless you checked with the club before and they are fine with it. However I doubt they are).
Other than that you can make banners and even displays a lot cheaper if you don´t just buy them (for whatever reason the whole buying banners thing seems to be the norm in England?), but paint them yourself.
Get an overhead projector and even if you are not an artist you can get some stunning work done. Cheaper, looks good and its something you can be proud off as you didnt just buy it.
Good luck with everything!
Keep doing what you are doing and don´t let others talk you down. Rome wasn´t built on a day, right? :)