The three accessories you mentioned are extremely easy to install, so don't be afraid to purchase those items on EBay and take on those installations yourself. As mentioned, only purchase factory OEM accessories, don't buy the aftermarket stuff.

Just like any other service, if you let the dealer do it (and hence let the dealer take on any responsibility for screwing it up), expect to pay for that service. For example, I installed my own rear lip spoiler, which included drilling holes in the trunk lid, and I did end up putting a small scratch on the car. but if the dealer had made that same mistake, they would be painting the trunk lid to fix the problem.

CAMRHEE Hybrid
Completed Mods: RK-Sport body kit, 18" LexusGS430 wheels 235/50ZR18 tires, TRD/SE springs, Rear Lip Spoiler, Terk XM-Direct, Smoked tail lights, Sliding Armrest, Rear Bumper Applique, Front License Bracket, Lower Grill chrome inserts, K&N, Blaupunkt THB200A sub, moved rear HSD emblem
Future Mods: fog lights, black chrome my wheels

http://www.greenhybrid.com/share/fil...fterFront4.JPG