there is a reason that they call it eurocrack
it's because it's gonna be a near-constant drain (however small) for the rest of your life if you get into it
it has advantages over lots of other similar endeavours in that you may actually have something left to show for it and it probably won't kill you, but never the less it always ends up as - what's the next module (or modules) and where is the next case coming from, often at the same time - unless you have near unlimited funds
your maths is way out with buying a second case!!! I kinda knew EU prices - but I just checked sweetwater for US - they are about the same
2 * Nifty case $538 168hp = $3.20/hp
1 * tiptop Mantis $335 204hp = $1.64/hp
with the left over you can buy a better midi->cv converter - everything else in the nifty case is superfluous and can easily be replaced for under $30 - a passive mult and a 1/4"->1/8" cable (and you may still have money left over)
so buy the bigger case - you will need it - imo 84hp is ok for 1 voice, once you add in the support modules you need to get it to do anything interesting, you may be able to fit 3-4 in to a mantis, if you choose wisely
as for the 'bundle' - why would you waste even $60 on modules you probably will not want in 2-3 months time
put the money towards something you do want - such as a better case or modules
once you have about $1000 to spend at once get the case and a couple of modules
as starter modules -
Rings - get an OG - pay some respect to Emilie for designing it and it has a massive advantage that you don't need a filter or vca after it
Maths - how to learn modular synthesis in a single module - well not quite, but as patch-programmable analog computers go - it's a great module!!
if you want midi sequencing get a midi->cv module (mutant brain if you can find one is a good buy) or maybe a korg sq-1 - I think it can do midi->cv too, but don't quote me on that - they are inexpensive and handy to have around
and that's it - work your way through the illustrated maths manual a few times, try all the easter egg modes of rings, next module should be a quad cascading vca - veils for example - then you might want to think about exploring disting (I'd try to get the EX if possible)
every week / month throw a bit in a kitty and when you have enough for the next module buy it - then patch it with everything else and work out what's missing and repeat!!!
or as @farkas suggested get a crave
"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