I agree with a lot of what Laura (rhubarbgirl) said.
Honestly if I stick with item X must have A, B & C and yet I don't find it, I have to realize what I want is impossible and possibly shift entirely what I'm looking for. So I guess I really don't get the HEWI, it seems to be a Ponce de Leon endeavor.

I do not have a problem with getting items altered to fit perfectly. Hems, waist bands, sleeves are simple alterations. I prefer to have items taken in (rather than let out) and do not like altering the shoulder line of garments - as that can be trickier for dressmakers to get right. I have sensitive skin, so if something irritates my skin, then that is non-negotiable. In your situation, a migraine is so awful, I would keep well away from synthetics.

I think it's okay to relax the standards on things that can be more trendy, such as tops or accessories and casual wear.
The one area where I can no longer compromise is with shoes. I simply cannot wear those cheap plastic shoes, even if I love the trendiness or perfect color of some things. They might only cost $25 but they will be agony all day and worthless in the end.