Sewell, Park Place, Carson, Irontoad (aka Thompson Lexus in PA), Lexus Parts Mall, etc. shop each of them and buy from whoever is the cheapest. Unbolt the shock mount (some unbolt the shock too; I find that unnecessary), mark the alignment washers on the strut rod, and then unbolt the strut rod's nuts and bolts. It's a very easy job.
Where is the shock mount? Is it accessed in the engine bay?