I'm pretty sure the shocks and struts were just Bilstein all of which are still available. Don't forget the quad shocks, I think Roush just used the OE ones but they're for sure dead by now. KYB and Bilstein both make nice ones and Monroe makes uh.. cheap ones.
The rear control arms are just tubular steel (I've seen Roush labeled ones both square and round tube.. not sure what that change is about) and the front lower arms look stock - probably M-3075-D ("Cobra") arms which have a few minor differences from the GT/V6 arms. I'm pretty sure those are discontinued but if yours aren't rusty you can push new bushings and ball joints into them or a set of BMR tubular arms would fit the bill.
For the rear arms you can likely just put new bushings in them, the arms themselves don't experience any wear unless something went very wrong. Back when these cars were new I don't think anyone including Roush was doing 3 piece urethane bushings so they would just be the relatively inexpensive 2 piece ones. Don't forget the upper axle bushings (not part of the arms). If you'd rather do whole new arms there are tons to choose from and bushing choice is the largest differentiator among them, now you can get lightweight aluminum arms too. Ride height is unaffected by brand choice.
The rear sway bar does not use bushings, the front sway bar bushings should be widely available just measure your bar diameter.
If your front spherical caster/camber plates are worn (unlikely) or the bump stops are split (possible) there are a number of options, Maximum Motorsports would be a good choice.