Congratz on your new tiel planned purchase! What kind do you have in mind? Might I suggest a Lutino male if you want a singing character, or a female 'tino if you want quiet. Or regular greys or speckled! Or a pair!
When you do take him home you should leave them in their cage for 3-5 days to grow to their new enviroment. Leave cage door open on flat ground incase if luckily he gets curious.
Oh and when you purchase a tiel the owner will well should ask if you want his flight wings trimmed, if they are trimmed they will be easier to handle.
For toys I use anything colorful I have not purchased any toys from the petshop mostly because thet look like they have regular paint and not the specialized untoxined kind. I have used a number of handles for buckets and hangars lid tops and wood. I have a lego piece in there but I am not quite sure if its safe.
Are you looking to buy a young weeks old tiel or adult?
Oh and if your going to purchase a cage a squared/rectangle whatever just that it has angles so the tiel will feel secure if it choose to hide or retract to a corner, whereas a canary cage which is a basic cyclinder cone he cannot.
And Im sure you know but the price range for tiels goes by their colour so hope you dont get ripped.
He's getting a youngster! He doesn't have to be caged up for 3-5 days to acclimate!!! You can have him out the first hour he's home with you. Cockatiels get adjusted pretty quickly to their new environment, especially since it is a youngster your dealing with, they're very curious!!! ONE thing you should do is try to leave a night light on for a week or two. Cover his cage would be wonderful. The reason why I said that is they tend to get night fright pretty easily! Having him/or her clipped would make it a lot easier on you to handle him/or her to begin with and with the first molt you can let them grow back if you like. I always clip youngsters after they learn how to fly so I can train them, then I let them grow back.
Toys like it was mentioned in Autumn's quote, anything pretty much! They LOVE bells!!!! And anything shiny!!! They also love swings. Provide with some mineral block on the cage. Food is up to you to decide!
Picking the coloring of the baby is up to you as well. As everyone have different thoughts on the coloring part. For me I tend to not get greys, but I've owned greys before in the past when I used to breed them. Each one of them have their own individual personality, no two birds are alike! It just depends on what you like as I'm not going to pick one coloring of the bird over another.
IF you read my recent post of my Cockatiel hatchling, I really don't care what color they turn out to be as they're all precious to me. Plus I'm not keeping any unless my partner wants to keep one, there's 5 eggs, 2 hatched already and third one is hatching Saturday. Fourth one on Monday and last one on Wednesday. That's if they all make it. Cause 4 families I have told they could have one but it just depends if everyone hatches.
Good Luck with your baby, post pictures once you get him/or her. Remember, only boys sing!!!!