Upload & Sell: Off
You might want to try using "Save for Web & Devices" in PS to save your Jpeg if you aren't already. You may get a warning when you try to do it if the image is large but it usually works OK for me anyway. The advantage of SfW&D is that you have all the controls right there for what you are trying to do: resolution/pixel size, Jpeg quality, etc.. You also have quality comparison preview windows that you can use and it will calculate an estimated final Jpeg size for you.
A possible work flow would be:
- With your image active in PS, select Save for Web & Devices.
- Use the Jpeg quality parameter to check initial quality and get a feel for the possible file size. You can also use the 2-up and 4-up preview windows to compare quality settings.
- If quality degrades too much before you reach your target file size, then use the Image Size parameters to start reducing pixel size. There is a handy percentage field that will reduce or enlarge proportionally, retaining your crop ratio. Once you change the Image Size parameters, you will need to click on the preview to calculate the new estimated file size. You can even up-rez using this method.
There are other parameters for controlling the embedding of the color profile and metadata. Not embedding the color profile usually saves you about 4k, which really isn't much. It's usually worth embedding the color profile to remove all doubt as to what color profile was used.