I can see it now:
$1.99 to increase max surface speed
$1.25 to increase torpedo effectiveness
$.99 increase morale
$1.25 reduced fatigue rate
$.99 expert reload increased reload speed
$.99 expert gun crew
$1.99 deep dive
$1.99 longer lasting batteries
$2.50 expert watch crew
$.99 gramophone player with 4 period songs!
$4.99 fifty song gramophone pack
$1.50 prewar training mission expansion pack
$2.50 paint scheme pack
$4.99 conning tower emblems pack
$2.25 sound FX upgrade
$6.00 graphics upgrade
Before you know it you just paid $200 for SHIII w/ GWX