Like most have stated before.... Getting to 700 hp for a couple dyno runs or holding 700 hp for 10 years is two totally different things.
I've had some great talks with Jason about this and he gave me some great advice.
With the technology, you can throw some fuel, NOS, turbo, and HPOP at a forged motor and break the 700 hp mark for cheap. Sooner or later, the block or rods will say FU.
What I've found is that you can budget for $15k for a motor and then just throw on another $5k for good measure. The little chit really adds up.