Hello, Mangoman! Welcome to the forum!
Well, it depends on how long you've had him if you want to return him. At the petsmart in my hometown, they give a 14 Day gaurantee notice, which is basically saying that if you are not satisfied with your pet within the 14 day period, then you may return it and get your money back.
However, there are other options, I believe.
First of all, how long have you had him? --->> It is natural for a parakeet to be still and silent for a few days. Because of my budgie's circumstances back in September when I first got him, it took at least a week to get him to become comfortable. So, don't feel frustrated if it is taking a long time.
Second of all, have you attempted finger training? --->> Finger training takes a lot of patience and time. You should start out with talking to your budgie softly and putting your hand in the cage for a few minutes and then removing it to let him know that you are not a threat. Note: A parakeet does not trust right away. It takes a great amount of patience!
Third of all, do you have a mirror for him? --->> Single birds should have a mirror near by to feel comfortable. My budgie has a mirror and he is completely content with the other budgie that is inside of it. However, if you want your little friend to befriend you first, then you should remove the mirror during finger training or not have one in at all.
Fourth of all, how big is the cage? --->> Single birds do not need very big cages unless they are going to be in one 24/7. (Which I do not recommend keeping a budgie in a cage 24/7 if you want him/her to have a good life.) My budgie is not in a very spacy cage right now, because I have him out most of the time for excercise and fun.
Clipping the feathers while you were at the store was, indeed, probably not a good idea. Capturing and being thrown in a box is already stressful for the bird itself. You could have probably clipped the wings yourself. There are lots of helpful sites online. Just google 'parakeet wing clipping'...you will get diagrams of the wing and the place you should cut along without causing injury. Anyway, we can not change the past. What's done is done. The bird is at your house now and it is your job to make your budgie as comfortable as possible.
I admire your compassion. It is good to think about these things, but there are better options.
There are many people who can help you on this forum and I'm sure they can add something that I have missed.
Hope everything goes well!
~ Jazz and Jess