Thanks everyone! I decided to place my order (and faith!) with NEXAPH. Was $357 including card fee and the 15% discount code doesn't apply to promo items. However, communication with
@Cain_SPC was really pleasant and his business appeared quite open and transparent (as far as I can tell).
SYR and QSC seemed trustworthy too, and $100+ less, but shipping times were an issue for me. I spoke to Amopure too (as someone suggested), but they don't presently have 30mg Tiz located in the US and tbh I was dubious about their testing.
Had I not left this order to the last minute (need the 10 vials within the next 18 days), I could have saved quite a bit of money. Although, if I am happy with Nexaph I'll probably stick with them (and keep an eye out for future promotions).