Mr. Frederick's advice is helpful, but in Arizona a power of attorney will not prevent your wife from "blowing money." It will allow you to make arrangements (pay bills, set up care) for her, but will not stop her from doing what she wants. Only a guardianship / conservatorship will prevent her from doing whatever she is inclined to do.
Arizona Guardianships require several different papers to be filed with the court, several different people to be appointed by the court to meet with your wife and file their own reports with the court, and a hearing to be held by the court. Your first step to try it on your own is to download the forms from the self help center of Maricopa county courts at http://www.superiorcourt.maricopa.gov/SuperiorCourt/Self-ServiceCenter/Forms/ProbateCases/prob_group_1.asp.
The forms and process can be intimidating; it is a complicated process. Seeing a lawyer once you have reviewed the forms would be a good second step.
As a side note, it sounds like you are the same person that posted the question on "spendthrift trusts" a few days ago. I hope you are able to get your situation resolved. Let me know if I can help.
If the spouse is still competent, I would have her execute a General Durable Power of Attorney form. This would name the husband as her Agent to handle any business affairs that she is unable to handle on her own. There are two general types of forms; those that take effect as soon as they are signed, and those that do not take effect until the principal is declared incapacitated.
In your situation, it might be best to obtain a Power of Attorney that takes effect right away. That way, the husband can assist, as needed, but there would be no need to have the spouse declared incompetent. That can be an uncomfortable and stressful situation for everyone involved, and it could also require court proceedings.
The Power of Attorney should allow the husband to act in the same manner and with the same authority as a conservator/guardian, without the need for probate court involvement. This will save a great deal of money and will eliminate the need for annual court filings. It is also a private family arrangement, and does not require anyone else's consent or approval.
The cost of a Power of Attorney form is relatively nominal. You want to make sure that you have a "durable" power of attorney because otherwise, it would cease to have any effect, if the wife becomes incompetent. You also want to make sure that all of the couple's estate planning is in order. Do not forget about the husband's estate plan. He should have a Power of Attorney, as well. It can be very stressful caring for a spouse with Alzheimers, and I often see the caregiver spouse having their own health issues, due to the added stress and strain.
If the spouse is not currently competent to execute a Power of Attorney, or if the Power of Attorney is not sufficient to address the spending issues, then court involvement might be required. The "advantage" of the probate proceeding is that the principal (or ward), is declared incompetent and any contracts that they later enter into, or try to enter into, can generally be voided.
Best of luck to you!