i need sway bar & links, control arms and caster bushings. which is most crucial

Get a second opinion to determine which are most needed. The links can be very noisy are are the least expensive to replace, and you don't need an alignment afterwards. The others are very important if they are really worn out, which they may or may not be. Get another opinion and ask them to help you prioritize. An honest shop will let you know which is most crucial.

Definiteley get a second opinion, I dont believe you need all that work at once....