something i'm surprised nobody mentioned is aftermarket wheels. if your wheels are not hub-centric then they will shake no matter how good your balance job is done. some lugnuts help mitigate the lack of hub-centering, but not always.
let's break down all the possible causes for noise and vibration in the front of a camry:
it's hard to check for a bent rim yourself, but you can do it on the rear easier than the front. block the front wheels, jack up the rear and do not set the parking brake. spin the wheel (or have someone spin it - kids are good for this) as fast as you can by hand and look for bends (they show up as wobble in the rim) as it spins. it's almost NEVER bent on the outside edge - it's the inside that bends the most, so look for this wobble under the car. you can try it on the front too but that's a lot more dangerous since in order to spin it fast enough to see a wobble, you pretty much have to run the engine in gear with the wheels off the ground.
wheel weights falling off or shifting (usually due to trim rings or hubcaps, or sometimes bumping a curb while parking) is rare but it does happen. but when you get the balance job done 43 times and it still does it, that pretty much rules that out.
worn ball joints will not make the steering wheel vibrate. they will show up as slack in steering and/or noise and scary "wobbly-ness" when hitting bumps.
bad strut bearings make a grinding/scraping noise while steering (mostly at parking lot speeds), and maybe a rattle in the front end, but cannot show up as a steering wheel vibration.
siezed calipers or slider pin(s) will wear pads unevenly and/or prematurely and make hotspots on rotors - you'll see blue-ing or actual chunks of brake pad material on the rotors. it'll also often pull/drift towards teh side that's siezed. this means warped rotors, which shows up during braking above 30mph in most cases. if the rotors are warped bad enough, they will cause steering wheel vibration even when you're not on the brakes, but in those cases it will get WAY worse when you do apply the brakes - we're talking rip the wheel out of your hand level of shaking. when it's this bad you can't just turn the rotors - you have to replace them, the pads, and rebuild/replace the failed caliper and its sliders.
worn lower control arm bushings will give you noise over bumps, slack in steering, and clunking noises when braking. they cannot cause wheel vibrations except on certain road surfaces, and then it will be intermittent, not constant.
worn/sticking/failing CV joints could in theory cause wheel vibration, but it would do it at all speeds, not just 50+.
some CV shafts have balance weights stuck on them (it's rare, but they're out there) just like RWD driveshafts have. if the weight was removed (vandalism) or came off (road debris/poor workmanship), this would definitely cause wheel vibration independant of braking. look for square clean spots on the axle, usually with a small divot in the center from where the weight was welded on.
a slipped radial belt in a tire could cause vibration too, but this will show up when you spin the tire on a machine as a lump or sideways "blip" in the tread, and you'd be able to feel it (most of the time) as if something was stuck to the tire while rolling at parking lot speeds. It will also usually pull/drift towards the side with the bum tire. tire rotation will help you isolate this - switch tires left-right and see if the pull/bump follows it.
ahh the things you learn while being a mechanic...