[nkb]

Originally Posted by 1985 CCX

My $0.02

KMS/CSX are the same car in alloy and will be well north of $100k to start particularly if you are going buggy spring.

Remember std KMS is like an ERA 289 car, a hybrid using a 427 chassis.
KMS upcharges for buggy spring chassis Big$$.

SPF is a great option as its both CSX glass and SPF using buggy spring chassis.
I love ERA cars but I would pay the extra few bucks for SPF as its buggy spring and not a Hybrid chassis. More correct. Glass CSX cars are SPF cars.....

Top down:
CSX alloy expect finished price >$175k
KMS alloy expect completed at >$150K buggy Spring ($125k hybrid chassis)
CSX glass ~ $140k buggy spring
SPF glass ~ $110k buggy spring
ERA glass ~ $70k glass / hybrid chassis

Of course I menatlly added things for correctness which could change $ but this should be about right in the end for decision making purposes.
The base car is mearley the start as motor, trans, wheels, tires adds $$.

It would appear that your prices are too low for the CSX alloy and KMS. CSX alloy roller starts at $181K. The KMS roller(billet suspension) is $200K. KMS finish (polish/brushed) - plus $25K, leaf spring suspension(recommended) - plus $10K. KMS appears to easily exceed $250K with engine and trans.