Please do not put ANYTHING in the bottom of your bird's cage (under the grate only, never on top where they can get access to it) except for sheets of either newspaper or Butcher's Paper, and that's it. Sheets of Paper only!!! There are actually several reasons that you just cannot use ANY TYPE of animal "bedding" at all, such as any type of wood chips, pellets, corn-cob, crushed walnut-shells, shredded paper bedding like the "Carefresh" stuff, any type of litter, etc.:
#1) They ALL trigger hormonal-behavior in all species of birds/parrots, just by them being below them and them seeing it, even if they can't get a hold of any of it...Anything that looks like or could be used as "nesting material" will trigger their sex-hormones, and with Budgies specifically, who are not supposed to naturally go through puberty until they are around 1 year of age, they tend to be sent into puberty much earlier by any types of bedding/wood chips/shredded paper, etc. AND by putting ANYTHING in their cages that create SMALL, DARK PLACES THAT THEY CAN GET INSIDE OF/UNDERNEATH. These include any type of Boxes, Tents, Beds/Triangle Beds, Hammocks, and the literally deadly/lethal "Happy Huts" and "Cuddle/Snuggle Huts"...Let them sleep on a perch, they don't need any type of bed or "Hut" or "House" to get inside of...
#2) Even when bedding/wood chips/pellets etc. are underneath the grate of their cage, they still manage to get pieces of it up with their beaks, and this will result in them eating them. It always happens, and with most wood chips and especially with the pellets, the corn-cob bedding, and the crushed walnut-shell bedding, they cannot digest it, it causes a blockage inside of their Crop or Intestines which will kill them without surgery to remove it, and in the case of the crushed walnut shells and the corn-cob beddings they can actually be injured/cut by their razor-sharp edges and suffer internal bleeding.
#3) Birds are extremely sensitive to any and all scents and fumes. Period. From anything. And most beddings and litters have some type of aromatics that they radiate, and with the bedding being directly underneath them 24 hours a day, they are breathing-in that stuff all day long, every day, and depending on what it is it can cause anything from an Upper-Respiratory Infection/Irritation to death.
So just line the bottom-tray of your Budgie's new cage with either sheets of Newspaper or Butcher's Paper and that's it (NO SHREDDED PAPER, like "Carefresh" either, it's a perfect nesting-material for them and will trigger their sex-hormones almost immediately)...It's easier to use sheets of Newspaper or Butcher's Paper anyway, you just remove the top-sheet that is soiled in the morning and put a clean sheet on top, and you're done for the day! (or dedicated bird-cage liners if you want to spend the money on them, but no reason to)...That's the other thing, using any type of "bedding" or absorbent litter, shredded paper, etc. is way messier and causes much more work because you have to be constantly scooping it out and dumping more in...
***And Newspapers are FREE!!! I stop-in to a local convenience store once a week (Sheetz in my neck of the woods) and grab as many of the "free" Newspapers they have, like all of the Ad Bargains, Bargain Sheets, Auto Traders, and all the rest of your local "Penny-Saver" advertising newspapers that are free! You can take as many as you want to take for FREE and you never have to worry about spending money unnecessarily on cage-liners, bedding, litter, or whatever else...And you'll be much happier and thank us later when your Budgies aren't either becoming extremely aggressive/violent and biting you all the time, or they are aren't constantly humping everything and everyone, and especially when your female Budgie, if you get one, isn't chronically laying infertile egg after egg after egg after egg all year-round, as well as when she doesn't become Egg-Bound because the bedding/wood chips or pellets in the bottom of the cage is keeping her in breeding-season all year round, and then you have to pay a couple thousand dollars for surgery to remove the egg, or pay to euthanize her, because once they become Egg-Bound those are your only two options...So just stick to using sheets of Newspaper or Butcher's Paper (if you happen to have a Butcher in the family), and your birds will stay healthy and happy, and you'll save money, time, frustration, and heartbreak...