Getting him into the cage at the breeders shouldn't be difficult because it is a familiar environment and if he was hand fed he probably already understands the step up command. Getting him out may be difficult but mine were so dazed from the drive home and new stimuli that they just obeyed the step up command automatically (again already learned from breeder). I personally would use the small cage if you can reinforce it sufficiently with zip ties otherwise you can use a box or buy a carrier. I would suggest big doors and something they can see out their surroundings. I have two carriers and I can tell a big difference in willingness to use them based on just those two criteria. You can still toss a blanket over the cage or carrier if it is cold or to make them feel more secure.
As for carriers I'm really not to impressed with what is out there on the market. I adapted a guinea pig carrier for Tico, my budgie, but he hates it. Grayson my tiel has an adapted cat kennel as his carrier and while he dislikes going inside he at least doesn't try to run away.