Rebuilds vary, depending on the condition of the internal parts when the trans is brought to them. At every rebuild, there is a kit that includes all the known gaskets, friction plates, and steel clutches. But there are pieces that these kits do not include, things like thrust washers (plastic washers that tend to be the first pieces that let go in a transmission), and other little tidbits.
After that, there are what are called "hardparts". These would include any gears, shafts, pistons, vavle bodes, and any other non-plastic pieces that are in transmissions. The rebuilder will clean and inspect all these parts, and toss out any part that is deemed unserviceable. This is why transmission rebuilds can vary in price so much. It all depends on whether or not the transmission just needs to be freshened up, or needs a complete overhaul due to lack of maintanance or abuse.
EDIT: Some transmission shops will teardown, inspect, and diagnose for free. BUT, the labor and parts to put it back together isn't. No shop can tell you exactly what is wrong with a transmission w/o tearing it apart first, which makes trans rebuilds an "all or nothing" affair.
Welcome, downwardly mobile yuppies, to the dawn of the Age of Nefarious.
1993 SSEi - FrankenJinx - dead and gone.
1994 SSE (136K strong) - 180* t-stat,HD alternator, most unequipped SSE on the club, XM radio, Kenwood CD/MP3.
2006 Chevy Malibu Maxx LTZ - Custom 2.25" manifold-back exhaust w/FM-80. Probably the only Maxx with this system.