For our partial basement finishing and HT project at our previous home in Lagrange, GA (Sep through Nov 2007), I found a drywall contractor through our homebuilder that was in a down-time situation.
We already bought the drywall ourselves (4' x 9' sheets), so we negotiated on labor (hang, mud, sand AND cleanup). They provided their own tape and mud. They charged approximately $21/sheet. The work included walls and one ceiling. They charged $10 per opening for a drywall opening.
The drywall contractor was also willing to do other work, including framing, wood trim, baseboard, suspended ceiling, door hanging, etc. Prices for these we negotiated separately. We DIY-ed the electric and AV work and insulation. Other contractors were hired to do the paint, AC and carpet.
All in all, we were lucky we got a very good rate from the drywall contractor. However, it was difficult to get them to complete the work right away. What would have taken 1 month was spread over 3 months, as they were timing their visits to coincide with other work in our neighborhood.
At the end of the project, they had used about 67 sheets of drywall. For our entire project, it cost us approximately $7200 labor and materials for 488 sq ft (includes a rec rm and an HT room). Note that we did not spend for flooring (only carpet on stairs), plumbing in stubbed bath, nor cabinetry in what would have been our kitchenette. We decided to relocate while we were in the middle of the project!
Here's a link to our photos, if anyone is interested.http://www.kuapao.com/basementfinishingproject