Well, I have a little bit of a different experience with my bird purchases.
We purchased our birds from Petco, 1st a Lutino Cockatiel, she was sold to me as a male bird, but within days, I knew I had a female. No big deal, she's sweet as pie. She was not hand raised and Petco employee's had been working with her a little bit, so she'd step up on your finger. She's an AWESOME girl! We love her to pieces.
Our 2nd bird, we also purchased at Petco, not planning on buying another, my husband walked around the corner and saw this poor little tiel in the stark white cage that looked like an Insane asylum to us....this guy was TERRIFIED of human contact and wouldn't even sit on our finger for a split second, but hubby couldn't leave him, so we bought him and brought him home. His name is Chicken Little and within 3 weeks he was not only willingly coming out of his cage to be with us and perching on our hands, he was talking up a storm! He's also AMAZING!
Our 3rd bird, was also an unplanned purchase...our Conure, Franklin. He picked US and we're so glad he did! He, however, was hand fed and handled a LOT and was only at the pet store for 7 days.
I have had absolutely NO health issues with any of the birds we purchased from Petco. I've had no problem taming down the 2 tiels we purchased. They willingly eat just about everything I put in front of them. They are happy, healthy, well adjusted birds. You can see picture of all 3 of them in my profile.
In answer to your question, about buying a budgie from a chain store...well, my answer is in short. Yes I would. BUT, as with all 3 of the birds we bought, we were somehow "picked" by them.
So if I was in the market to buy a keet and I happened to be at the pet store and one stood out from the crowd and "picked" me. I'd have a hard time saying NO.
Oh, and when my daughter was about 4, I DID purchase 2 keets from a chain pet store, and we named them Bobo and Joker and somewhere I have a picture of my daughter holding them. They were our first birds and we learned a lot about bird care and taming and loved 'em dearly.
Good luck with what ever you decide to do, but I wouldn't entirely discount chain stores. In my case, I'm glad I didn't. Our birds are AWESOME!
Toni