1) The first stage is 2/3 the total cost to launch. Which would be $40 million.

2) They can renovate the first stage for $5 million.

3) They can get five launches from a first stage (original plus four more).

So, $60 million for five launches, plus the $20 million for the second stage x5.

Which comes to $32 million per launch. A bit more than half the current price.

Now, I consider those pessimistic assumptions.

Alternately...

If we replace (3) with 15 launches per first stage, we get $28M per.

If we replace (2) with $1M per launch, we get $29M for five launches, $23.75 per launch for 15 launches.

Big picture: reusing the first stage only will allow them to drop prices by 40-60%.

Now, if they can reuse the second stage also, we're talking some real money....