I think you’ve kinda? answered your own question. You seem to value a ‘potential’ trainer at a ‘potential’ barn more than a vet PPE or using that plus even your own decision. I realized I couldn’t understand it because I don’t want to be in a specific trainers care, or a specific barn either(!) in my journey. But I’ve never used a specific trainer or chosen a barn ‘for’ that trainer to board at either. I Know, enjoy, appreciate and have used trainers! But I admit rarely, and for a limited time for a young horse…not a board, ride, lesson with forever situation. (I kinda like a bit more freedom and less judgement on my horse purchase) But I realize if you want to ride/school under a certain trainer at a certain barn…you’re probably being wise to protect that. If that’s the case, I would work with this trainer and not preview horses ‘alone’…find one you really respect and trust and have that on board first. 
Sorry, somehow I missed this message! But you’re on the money with liking more freedom and less judgement - that’s exactly why I went off to buy a horse on my own without one in the first place. I was second-guessing my own ability, but now after going through the buying process, I’ve realized I know a lot more than I give myself credit for, and it’s so easy to just look stuff up if I don’t know the answer. And I am very much a people-pleaser to authority figures like trainers/coaches so I desperately want to stay away from getting stuck in more situations where I’m not doing exactly what I want to do with my own time and money! Thank you for the helpful advice
