I guess I need to refresh your memory about what I actually posted in response to YOUR original post, quoting race 9" pricing from Strange Engineeering. I didn't pick Strange, YOU DID!

Because the OP specifically said NO spool, I priced a bolt-in S-9 and S-60 street/strip assembly for comparison purposes:

New Strange-60 Dana 60 assy, forged steel 1350 yoke, choice of ratio, Strange-Trac differential and 35 spline axles complete with leaf spring perches installed $2225

New Strange-9" nodular iron case, aluminum pinion support, forged steel 1350 yoke, choice of ratio, Strange-Trac differential, 35 spline axles, fab housing with short back brace and leaf spring perches installed $3175

The price difference is $950. Both assemblies are built by Strange, with the SAME parts. Both are bolt-in units, both have the same axles, both have iron centers and forged yokes. BOTH HAVE THE SAME HIGH-END S-TRAC DIFFERENTIAL installed.

Because you have a problem comparing apples to apples, I updated the price quoted in YOUR POST with the LEAST EXPENSIVE 9" 35 spline traction differential available (Detroit Locker). This is the exact quote from your post, only substituting the spool for a Detroit Locker from Strange:

Strange sheetmetal housing with ends welded on - $525.00
Strange Pro HD center section with a spool, 4.10 gear, and billet yoke - $1245.00
Upgrade to Detroit Locker $300 ($1545 third-member cost)
Strange axles with bearings and 5/8 studs - $515.00
TOTAL $2585

Of course, you can pick the cheapest imported 9" components, coupled with the cheapest 35 spline traction differential, assembled by a buddy for $100 to get the price closer to a US MADE S-60 assembly built with a high end street/strip differential.