My suggestion would be to go to drywall supply company that the Commercial Drywallers use. Many of them will have everything you need along with a great deal of knowledge. You most likely won't get it at the prices like we get b/c we have to have accounts and be a LTD company. But given you economy they might be hurting enough to give you a pretty good discount. Besides, the bigger discount at a big box store may not be as valuable as the educated and free advice. I know if my husband was in a store and somebody came in asking questions he'd help. And you only get what you need. If you have a difficult time call a few Commercial Drywall companies and ask them who they use for a drywall supplier. if you go with a grid ceiling, buy 2x4 commercial tiles cut them in half and do 2x2 grid, will look professionally done and they are really nice. Get a water leak and replace a tile not a soggy, likely moldy sheet of heavy drywall.
If you are looking at cost then I will suggest looking at doing R-30 insulation between the joist that will be about .50 cents a foot.
Install the RC Channel perpendicular to the joists at 16"oc, use 1-1 1/4" screw to hold it. That will be about $1 a lf of channel.
Try not to put anything in the ceiling like can lights, but if you do have lights in the ceiling I would suggest boxing them in and install 5/8 drywall inside the box, then add the light and seal any penitrations. This may create an overheating problem with some lights be sure to check out what lights you get.
You can go more expensive then this but this should do a good job for the money you will spend.
If you want to spend more then start with the joist bay and look at doing Mineral wool or Knauf Fiberglass acoustic board below the insulation that will add another $1 per sq'.
Make sure you seal all gaps, holes, and any penitration.
Your budget sets what you want to do.
__________________ "Yeah, it's a nice garage, but you have to keep it heated at all times so it doesn't mess up your roof line."