Parrots in general are very expensive long-term, not just up-front. Getting a bird and the cage is one small part of the total cost. The bigger the parrot, the higher the cost, but none are cheap long-term.They need to visit an avian certified vet at least 1x yearly (with blood work early on and then every 3 years after). In general, something goes wrong (be it a bacterial infection, blood feather, virus etc) and so I would make sure that at any given time, you can drop $500 on a vet bill, because between the wellness exam and other visits, you are looking at around $300-$500 a year just at the vet (barring any major emergencies). This could easily jump into the "thousands" range in the event of an accident or serious illness.
Their food, toys, perches, play-gyms etc also all cost money (toys need to be stainless and the need safe wood toys to destroy-- the plastic cheap ones are not enough, and mirrors and hammocks/huts should be avoided). The toys need to replaced often and having play-stands/gyms in other areas of your home is also important.
If you get a powder-down bird (gray, too', cockatiel) you will also want solid, true hepa air purifiers (non-ionizing, non-ozone producing/non sanitizing) due to their feather dust--A u2s dust is SERIOUS. Replacement filters cost money too.
The cage for a cockatoo will run around 500-$1000. For a cockatiel, the cage would be $100-$300. Bigger toys and perches cost more...Make sure you replace any dowel perches with irregularly-shaped manzanita, dragonwood or custom perches (parrotWizard.com) because the smooth/dowel ones lead to bumblefoot.
She will also need to probably throw out or replace a large part of her kitchen because teflon/ptfe/pfoa/pfcs used in many non-stick pans, but also in appliances etc can off-gas when heated and kill parrots even if the bird is on another floor of the house with the door shut. Things she may need to replace: pots, pans, dip trays, griddle, irons, ironing boards, poachers, popcorn poppers, air fryers, toasters, electric skillets, cookie sheets, muffin tins, toasters, toaster ovens, self-cleaning ovens, hair dryers, curling irons, straighteners, space heaters, heat lamps, utility lamp reflectors, some light bulbs, panini makers, George Foreman Grills etc .
Then there will be necessary changes to her cleaning routine and lifestyle: she won't be able to use standard cleaners without harming the birds sensitive respiratory system, and candles, air fresheners, oil warmers, plug-ins, essentials oils, diffusers etc will all have to be given away...So factor in the cost of replacing appliances/utensils and then replacing all current cleaners with bird-safe ones...She won't be able to paint her nails in the house, use glues, spray aerosols, perfumes etc.
Bottom line: They are expensive (more than a dog or cat) and they live longer...If she has any trouble with mobility, a bird will also likely be problematic, due to the amount of bending, reaching and general movement you have to do if you have one. Cleaning alone turns you into a question-mark some days. If she has any breathing issues, avoid powder-down birds altogether.
Once you determine whether this is a possibility financially-
A cockatiel is a close relative of the cockatoo-so close, they can actually reproduce-- and while they live a long time, they don't live AS LONG (more like 20--known people with a tiels in their 30s though).
A cockatiel is still just as smart etc, but they are not nearly as crazy as U2s and their bites are not nearly as damaging (although they still need to chew on wood etc). They are more "chill" (although don't expect a couch potato) are they are smaller, so their cages and accessories also cost less (although, again, still not cheap).
A cockatiel will still need a bedtime/routine, you will still have to make it chop and spend a few hours with it each day (just not as many as with a U2), not use teflon/fumes etc. If you do get a smaller parrot, make sure you get a cage that is plenty big but has appropriate bar-spacing. For a cockatiel, flight cages are generally a good option...
It's still going to need the yearly vet etc as well.