the bulk of your budget needs to go to LR
and a good skimmer. you probably should set up a sump. with enough LR
+) , you don't need any other power filter like you do with FW
. you should aim for 10 to 20x flow (900-1800 gph
for a 90g) LFS
overcharges a TON for skimmers, so look online. marinedepot is a good place for deals.
If you're on a budget, hirocks.com will cut your LR
cost, and good aragonite playsand saves over LS
. Be sure you don't get silica sand though.
mostly, you need to read and take your time. there is a lot to learn, but it's not as hard as people think sometimes.