The most obvious place for you to try, given your location and keeping things within the local economy is Peak Imaging. I find ProAm Imaging to be cheaper and, possibly, better. There are a lot of labs who are all capable of doing a 'good job'. If you cannot find 9" by 12" prints, just increase the canvas size to the next print size up, 10" by 12" for example.
Whichever lab you use make sure that: - you download their colour profile and convert your images to that profile - you supply them with the image file sized to the correct pixel dimensions