A neurologist is often the primary treating doctor for TOS and will probably give you more attention on office visits.

there are several good ones in LA- check out the doctors list.

TOS will not show up on a normal MRI- so unless you are trying to rule out cervical disc problems, i would skip it.

Dr Jordan does a very nice ultrasound- with or without a scalene block to very accurately diagnose TOS. The ultrasound itself is not all that expensive, and you can Check on the charges for the scalene block (i don't remember, sorry) but it is definitive and might be a lot more efficient route to travel than seeing many docs who don't care or another doc who would send you for the $12000 MRI/MRA that dr collins does. If your insurance won't cover a regular MRI i doubt they'd cover that sucker.

best to get it figured out so you can figure out how to get better. I think Olecyn is in your direction and has found a PT that she likes- maybe she could offer up a name.