Thinly ground, ~5" fixed blade without going custom?

[pinnah]

Look for older Western or Schrade USA fixed blades. Can often be found dirt cheap. Generally stick tang with leather stacked handles or wood/plastic handles but also generally have thin 1095 blades and often with a versatile sabre type grind.

An example:
Schrade-Walden H-15 by Pinnah, on Flickr

 

[Murindo]

The South Fork would be perfect and comes with a great sheath. Another good Spyderco is the Perrin Street Bowie in VG10 for under $100

 

[Lycosa]

Svord fixed blade with that very sharp L6 tool steel.
rolf

 

[brownshoe]

Queen, Case, Buck make new old style knives that will fit your bill. Queen is in D2. As Pinnah suggests, there are lots of Westerns out there that will also fill your needs. IIRC they are 1095.