tie/sway bars

Do people use tie bars and sway bars on the same car, or is it more like choose one and you don't really need the other?

they can be used on the same car, usually sway bars are only for the tops of the shocks and ties are for the lower rear area, while sway bars go front upper, and rear upper.

most peeps use both.

Alright, say I only have money (for now) to put 2 on - which areas would benefit me the most? I was thinking front/rear upper...

Sway bars are on the bottom of the strut and actually are connected to your control arms. Tie bars arent worth their money, get front and rear strut bars first, then get both sways, then get the tie bars, and somewhere in this mix you should upgrade springs, struts, and tires.

You can use the sway bar from a si crx on your car, you'll need the mounting brackets and the lower control arms from the donor car as well.