I think this is an important thread because it allows us to see the thinking and the decision-making responsible people make about adopting a parrot, so I am glad that you are using the resources of this Forum for that!
Let me say that I do not have a Grey--I love the 'idea' of one, but as you say, it is like interacting with a small person--a LOT of responsibility, and even with my lifestyle (work from home, etc), I do not think I could make the commitment.
But I struggled tremendously with my decision to bring my Green-cheeked Conure home, which I did nearly a month ago. I, too, 'accidentally' stumbled across this bird while picking up some treats for the dog. Within minutes, it was clear that there was something to this particular animal. I spent an hour with it. It was new to the store, less than four months old, and had only just begun step-up training with the staff, whom I had worked with before and liked a lot. It was also parent-raised, which had caused me concern at first (I got a lot of help on that issue in this Forum, including from people who have contributed to this thread!!). But in that hour, it was stepping-up for me, accepting treats as reward for stepping-up, preening itself on my shoulder, not being 'loud' (especially for a conure), and just seeming 'too good to be true.'
Needless to say, I didn't sleep well that night. So I went back again the next day. At a different hour, with different store staff, just to see. It went even better, for an even longer period of time. I went back again, the day after that, and brought a friend with me, again at a different hour with different staff, just to see.
After all that-- multiple interactions on multiple days and situations, with affectionate temperament, trainability, handleability, and an acceptable noise level--and loads of more research (I've been thinking about this for over a year and, like you, have had birds in the past), I took the plunge.
So far, things are great. Having the confidence of multiple visits in different situations over a period of days is very helpful.
Michael raised an important issue about its temperament OUTSIDE the cage. After I saw that, i realized that it wasn't clear to me whether you were able to handle the Grey outside the cage. And I think that is a big, big deal. It may be that the bird likes you--from a distance, and from ITS territory--but it may be a different story when it is in YOUR territory (your apartment, and on your hand!).
If there is a way to test that out, again a few times under different occasions and conditions, that could go along way.
The other thing I want to address is the concern about where to get the bird from. This was a big issue for me. Rescues have SO many good advantages, from seeing what a bird post-terrible-twos is like, to doing something 'good'. So, too, do breeders, depending on how much they are (truly) willing to work with you after the baby is home.
But I have to say that if the bird has 'chosen you', and you feel that you are 'choosing the bird', if the bird is healthy and there are no obvious signs of problems with the store and there is a good health guarantee to allow you time to get it to a good avian vet, then I think you should not feel 'guilty' about where you purchase the bird. Obviously, all stores are different--I do not want to overgeneralize at all.
In the end, the bird and your life need to take precedence over 'sending a message' or anything like that. The bird had no choice in where it ended up being put up for sale or adoption and we should not lose sight of that.
To sum up, I'd say to go back a few more times, see if you can handle the bird at all, and think HARD. You know your life and your level of commitment and how likely things are to change or not in your life--all of us can only remind you of what you already know: that your life is in flux right now and will be a for some time. But ou are going through a sound process of decision-making, and if you continue along that way, I think you will feel very good about which ever decision you make--that is the best any person can hope for.
Good luck to you!
