Check this out: www.countrykitchensa.com/whatshot/minicake.aspx
This is a web page of Country Kitchen Sweet Art. Photos and instructions are shown also on this page. They have mini cake pans that can also be used as chocolate molds. They are not expensive too, approx $5 each.
On second thought, maybe you can use molded chocolate "cake tiers" instead of baking cakes. Easier than doing it with fondant. And everybody loves chocolate! 
Wow! That will take you a while... I have some mini tiered cakes in my photos with a description of how I did them... maybe it will help.
http://www.intotheoven.com/p395/Round-2-&-3%22-2/Tier-Cake-Pan/product_info.html
i have some of these and they are cool for a few at a time, but i think the shallow or torted sheet cakes and cutters are a SMARTER option.
http://cakecentral.com/modules.php?name=gallery&file=displayimage&pid=388943
http://cakecentral.com/modules.php?name=gallery&file=displayimage&pid=520913
http://cakecentral.com/modules.php?name=gallery&file=displayimage&pid=593483
if you do sheet cakes, you can cut them with a cutter, put a swirl of filling or icing with a 1M tip and top with another, then do a dusting of powdered sugar or a poured ganache. maybe a rustic wrap of chocolate.... if its small, its going to be harder, and messier, so i would go for the purposeful rustic look. then add something really nice like a fresh flower or fondant/luster dusted pearls or fresh fruit. strawberries, blueberries, blackberries etc....
edited to add photos and to note that my cakes were done using the two tiered mini pan = 4" high
I saw some tutorial or article on here saying that for covering the mini cakes, it's good to have a chocolate mold. That way you can drop the little pice of cake in there and then cover it with chocolate or poured fondant and it would be covered uniformly and smooth. I had never thought about that.
I haven't done any large orders of single serve cakes, yet, because I price them so outrageously that they don't order from me.
I have heard too many horror stories.
Before you give her a price, make a 12x18 sheet cake and make as many from that cake as you can, see how much it costs and how long it takes. Then you will have an idea of what to charge.
Cut cake circles from chilled cake, then freeze for poured fondant icing. You can dip them into the icing that way. I don't do fillings on mini cakes because I don't have the cylinder molds.
Rolled fondant takes forever.
I did some mini cakes for a chritening and they were a PAIN! I baked mine seperatly in little mini pans, and they didnt all rise to the same size, so I had to torte 40 little cakes :O
I def didnt charge enough 
afterwards I thought it might have been easier to do the sheetcake and cookie cutter route!
I just made some 4" mini cakes covered in fondant to go with my daugher's wedding cake. It was a pain!! I would definitely suggest cooking a sheet cake and using the cutters. Like someone already mentioned, they don't rise uniformly and having to wash the pans each time (I have four 4" pans) ... ughhh. When my DH was watching me cover these (and remember, they were only one layer), we were talking about what I would charge for mini wedding cakes with two or three tiers. I had mentioned $5 and he said it would seem more like $10 per cake!! It will be a lot of work -- don't underprice yourself!!
Tina_mace.... I forgot about the washing up!! 
horrible
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