4" babies are too small to buy from anywhere. They are barely out of the shell, may not even have eaten much. Then they are boxed up and shipped to a petstore then crammed in a little 10 gal tank with a whole bunch of other dragons. On top of fighting for basking heat, uvb light and food with all its cage mates, now that little bearded dragon has to deal with kids banging on the glass etc.
So, when bought by people these dragons are already highly stressed, half starved and terrified. Then they are put into a totally new environment...it is much more difficult for these delicate dragons to bounce back and get back to what baby dragons need to concentrate on, eating tons to grow. Not something for the first time bearded dragon owner to deal with. Much higher mortality rate, not necessary from mistakes by the new owner.
Waiting till the dragons are 6" long and about 6 weeks old, ensures the dragon is well established and thriving. They also have more reserved fat to tolerate a couple days of little eating as they get used to their new home.
Reptile shows are the best place to get dragons, more choice and you get to talk to the breeders themselves and most are quite willing to answer questions not just at that time but in the future over the phone or email (though some breeders may be very busy and may take a day or two to answer back...really depends on how email they get. Most do try and respond promptly though.)
The events tab above will show all the reptile shows coming up all across North America, so you should find one. There are a couple shows that go to Chicago...when and where i don't know..Just remember seeing ads for Chicago shows in Reptiles Magazine. A reptile show is a great place to bring a girlfriend and wife to be to see reptiles, especially if they are a bit nervous about them (if she has phobia of any reptiles..not a good place to take her or course). Many breeders will allow prospective buyers to hold animals or at least touch them while they hold the animal. Also, you can buy the adult cage at the show at the same time. Many big cage designers have booths at reptile shows, especially the big ones in the US. Asking about a particular show in your area in the forums can also reveal what sort of size to expect and what typically is there (breeders and suppliers).
Crickets can be ordered in bulk from many sources online. Under the Businesses tab above, you will find a list of breeders, feeders and supply sellers online with webpages you can check out and compare prices. The closer they are to you, the less shipping you will need to pay. If not sure, most sites will have contact emails and phone numbers for you to use to get more specific info.
Crickets can be stored in rubbermaid bins filled with egg cartons and fed either a store bought gut load, or fresh greens, crushed cat food, fish flakes, chicken mash and other foods. Thus you can order say 500-1000 1/8th to 1/4 inch crickets and feed them off as you go. The slightly smaller size than what you need now works good as it gives time for the crickets to get bigger before they get too big to feed (crickets should be the distance between the dragons eyes).
One last comment.
You mention in 10 months you will be getting married. Though it would be nice to get a bearded dragon before hand, but you already indicated you won't have time to build an adult cage and can't easily find a large enough cage in your area. But when people get married, the prep work takes alot of time, then the ceremony and usually followed by a one week or longer honeymoon. Who's going to be taking care of your dragon while you are away? Also, moving into a new house brings up its own share of problems.
I am thinking it may be better for you to continue researching the care and keeping of bearded dragons and wait till after you are established in your new home. It may mean waiting another year but then you will be better prepared to enjoy your new dragon and have the time to spend with him and build the adult cage.
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PHLdyPayne