I think this is a very short term solution - so I'd still get the bigger case - yes it's going to cost a bit more - BUT - if you are like most people you will want more as soon as you can afford it - and this way you are prepared...
remember you don't need to fill the case immediately or ever, for that matter - blind panels are your friend...
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities