An important thing to consider in any contracted job is the amount of time in labor. If you have a bare tub; ie, nothing to remove---and as a result you dont expect them to reinstall anything, you can cut most of these figures in half...especially with a FG tub...there will be some surfacing needed, but not as much prep as removing paint or prepping after media blasting. If you are expecting to pick up a ready to drive truck when the paint dries, then the figures mentioned above still apply, if not more.
I am approaching the blasting/painting stage...and this is what I have found...however, some shops will still not want to due a full paint job as it is still not as lucrative as insurance work...%). If you are planning on lining the tub, then the glass should only have to be properly primed--entirely, with jsut the paint on the major panels with some overlap where the delineation with liner is to be so the paint that there is a proper paint-liner overlap/seal...again not as important with glass, whereas VERY important with steel (or so I have been told/foudn in my research). Good luck.