i had to google crash cart... i see what you mean now.
actually micro-atx prices arent all that bad and are pretty widespread. micro-itx however tends to be a more expensive platform.
did a little more searching around
this case is expensive but is only 11 inches deep (micro atx though). its also fanless which might be a big con
http://www.quietpc.com/nof-cs-70
this case is only 13 inches deep (micro atx) and has a fan
http://www.newegg.com/Product/Product.aspx?Item=N82E16811163222
you might be able to get your hands on an atx motherboard htpc case with the right sort of fan layouts and turn it on its side and use it like a tower. many of them arent quite as deep (they stack components very tightly in the case). while you might be more limited in terms of graphics cards and components to pick from its shallow. heres an example
http://www.newegg.com/Product/Product.aspx?Item=N82E16811352028
http://www.silentpcreview.com/silverstone-gd05
another rather shallow micro atx case
http://www.newegg.com/Product/Product.aspx?Item=N82E16811163176&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&cm_sp=&AID=10487648&PID=1800524&SID=
the only cases i found which were reasonably shallow were media center/htpc cases for the atx form factor and of them there are not many which fit the bill. they would have to be turned sideways though and often have feet so it might look strange. they also might not fit all the components you are looking for.
if you are okay with going to m-atx (which is still not a bad choice and isnt super expensive like m-itx is) then you have a few more options to go with.