OK, let's follow the dollar signs:
Coming off the books
Ausmus, $4M
Bagwell, $7M
Biggio, $5.15M
Lamb, $2.7M
Loretta, $2.5M
Lane, $1.05M
Ensberg, $4.35M
Jennings, $5.5M
Miller, $1.3M
Palmeiro, $0.95M
Total money expiring: $34.5M. (Note that this does not tie to the $47M guaranteed for next year figure that Purp quotes; I assume that the difference is non-arb eligible players. In any case, my figure offers the Astros less to spend, so let's go with that.)
Additions or raises
Wigginton - 2007: $2.7M. Projected 2008: $3.5M
Lidge - 2007: $5.35M. Projected 2008: $6M
I figure they have about $32M to spend on FA, once you allow for a few other small raises. (Note: Lee gets paid $12M for 2008, and then $18.5M/yr thereafter).
$32M to get:
CF, C, 2b?, #2 SP, #3 SP, and bench.