Check out Montpensier Hotel. It's been a while since I stayed there and it was under $100.00 a night. I'm sure it's more now. Great location.. at the Louvre stop on the Metro. Small, charming and friendly staff. Good luck.
I've stayed at the Hotel St. Pierre at least a half a dozen times over the last 15 years and have always found it a great value and a convienent location. It is near the Latin Quarter and is about $100 dollars a night.
We stayed at the Duquesne Eiffel in April and found it to be very nice and very convenient . It's 2 blocks from Invalides and 3 blocks from the Ecole Milataire Metro stop. There are quite a few nice restaurants and shops within a few blocks also. The rooms are typical european hotel rooms . but many of the rooms have a great view of the Eiffel Tower. They also have shuttle bus service from CDG.