S.R.
You didn't mention whether or not your child was cared for by a home daycare provider or a center. I think in the case of a center, gifts are more modest - perhaps in the $25-$50 range. I also know that people that have nannies typically give about one week's pay as a bonus. Assuming you are referring to a gift for a home daycare provider, perhaps a home daycare would fall somewhere in between the two, but a week's pay seems kind of on the high end when you factor in the fact that the provider likely cares for multiple children.
Also, if you have only been there for a month, I think it is totally appropriate to not go crazy this year. People are scaling back on just about everything with the economy being in such bad shape. I believe the most important thing a provider wants deep down is a really nice note saying thank you. On top of that a gift certificate to somewhere like Target or a gift set from Bath & Body Works would be a good option. If it were me, I would probably think about something in the $50 range this year and maybe a more substantial gift next year assuming you have been there for a while at that point. Also, you can think about doing smaller gifts throughout the year (birthdays, other holidays) just to say thanks.
Best of luck!