I want through this last year (160K miles) and the short answer is that you'll keep chasing problems until all the components have been replaced - struts, strut bars, upper/lower control arms, ball joints, and tie rods. You're doing what I did - replacing 1 component at a time hoping that will fix the problem. In hindsight I should have done them all at once for I would only have to work on it once instead of multiple times.
So we're talking $2K in parts plus DIY labor or $4K at a mechanic. Is it worth it???
I had this debate for a while, and finally decided that it was worth it, for I coundn't find another model to replace it with (best car I've ever owned), the engine is still solid, and the cost of the repair is nothing compared to the cost of trying to replace the car. So if you really like your LS, I'd say do the full repair, since it'll ride like new again afterwards.
No different than those who own classic cars. When something breaks, they just fix it - they 'never' think of selling the car just because a part wore out.