just tell the shop owner
u wan a char kei setup
and u can only afford 1k

he will probably recommend u adams digital amps and woofers
or rockfox all these types of stuff

seriously, u dun need to change all these HUs
just some average comps, average amps, and also woofers will do
but seriously 1k will get u nowhere
installation alone will cost u at least 1/3 of ur budget