I think that you should spend more time planning and thinking, please don't buy stuffs yet , you would be disappointed. you have one voice and 3 expensive filters, that' like setting money on fire.
hexmix is also no right for such a small system.
what about you buy a cheap osc, a cheap filter, a cheap vca, as many utilities as possible and you learn from there ?
shapeshifter is nice but is definitely a complex module. chose one (or better two) cheap osc ?
remove two filters.
what's the plan for sequencing ?
do you know synthesis ? did you consider a semi modular ?
something like a beastep and a behringer crave, k2, or neutron ? that would help you building some basics.
a arturia minibrute 2s would also be a smart starting setup me thinks...
ask for more advices, read, test stuffs, and try not to spend too much money for now!