Superchargers aren't the cheapest things out there, however a good, new centrifugal supercharger can be had for 2500. The beauty is if your engine ever pukes, the s/c in not affected, can be resold, transferred to another car, etc. A used one can be had for 1000-1500 depending on model.
quickD100 has a post in the race section about how he took a stock LA 318, put on a $250 ebay GT-45 turbo, put in a new head gasket set, o-ringed the block, head studs and dynoed 563hp. Even with the extra complexities, it would be well worth for the cost savings. For 1000 bucks you could put the whole thing together. Worst case scenario you grenade the block and are out the $200 bucks for another junkyard 318.
You make some good points. What's interesting is that with a quick Google search, a brand new NOVI-1200 supercharger is roughly $3,000, so installing that on top of a low mileage 5.9 Magnum wouldn't be more expensive than rebuilding a big block with similar HP.
And correct me if I'm mistaken, but with a turbo you dial back the boost if need be and turn up the power whenever you want it.
Hmm...
