Between this
http://www.sdpc2000.com/catalog/2721...3-LS1-LS6-.htm
and this
http://www.texas-speed.com/shop/item...id=85&catid=36

 

Looks like about $18 bucks

The only thing different that I see, is there wasn't valve cover gaskets listed in TSP kit.

 

Looks like the GM kit does not include valve cover gaskets nor front cover gasket, whatever that is (they both list the timing cover gasket):
"Includes GM Timing Cover Gasket, GM Timing Cover Seal, GM Water Pump Gaskets & GM Harmonic Balancer Bolt"

 

looks like they are both selling you a bunch of gaskets that you don't need. Just get the bolt, the gaskets on the motor are reusable. The only gasket I've ever not reused was the waterpump gasket, and that one tore when removing it on a high mileage motor