Re: @ bazza
Oops. For 'billion', read 'million'. Hadn't had an early morning cuppa.
Anyway, to return to the point, for any half decent payload (big TV satellite, big comms sat) the owner would have paid anything up to $1billion building it. ENVISAT cost a reputed $2.9billion. Uncle Sam will quite happily spend $1billion on a spy sat. The one SpaceX blew up a few weeks back was a comparative tiddler money-wise, only $200million. There's a good book here, page 99.
In comparison, even an "expensive" launcher like Ariane will be ~$100million ($150million if one's satellite takes up the whole launch payload), Wikipedia's page is quite informative on the matter. And SpaceX are seeking to chop costs like that into tinier pieces.
It's been a long time since launches were more expensive than building big satellites.
Manpower. SpaceX seem to have no ambition to reuse a booster more than 1 or 2 times. That means that for the foreseeable future they will have to retain the skill base, currency, and capacity for something close to full rate production (assuming that a few don't make it to landing as planned). These are not talentless people who can be picked up off the streets at short notice, these are hard-to-find guys and girls who once you've got them you have to retain them, pay them, keep them busy, etc. It's not like they're necessarily jack of all trades either - they're specialist welders, machinists, etc, all highly specialised in their individual fields and not easily transferable to different roles. A lot of that skill base may very well be vested in suppliers' workforces, but it's there same problem all over again and the costs of dealing with it will be passed on to SpaceX and anyone else buying from the same supplier. Same for the factory - whilst there's a single final assembly building, there's a myriad of smaller plants all over the place that have to be kept operational if they're to build just one booster per year.
And on top of that SpaceX would need to have the refurb staff too to recycle the one's that did make it to landing. If, and only if, SpaceX can re-use their first stage many many times (e.g. 50 times) is it worth building a fleet and then standing down the production line.
This problem aflicts every major large engineering production project. Fighter jets - the unit cost goes up as the government's order shrinks for exactly the same reason. To get an empty cardboard box from Lockheed or SpaceX would cost almost as much as putting an F22 or Falcon 9 inside it. The F16 production line is about to close, and once gone it'll be veeery expensive to bring it back should anyone want a new build F16. The overhead of having the means to produce things this complicated yet not making them is almost as expensive as making them regardless.
And since you mention cars, it costs Ford / GM / Merc / etc. around about $1-6billion to develop a new car. Which is why there's so much platform sharing going on these days. Once they have developed it and set up the line they can churn out millions of cars for a couple of thousand dollars each (if that), but that first one is $1-6billion. Take a look at this.
Anyway, I'm only reinforcing SpaceX's own pronouncements on the matter, covered previously here on El Reg and elsewhere in the press. Take a look at this: SpaceX were talking about a 30% discount, tops. Even that seems ambitious to me.
So lets see... Say SpaceX charge $50million for a fresh launcher, 30% discount for a second hander = $15million saving. $15million/$200million = 7.5% of the price of the satellite that got blown up. That's pretty small beer. In the grand scheme of things, if one could ensure the success of an investment in a $200million satellite by spending an extra $15million on a fresh launcher as opposed to "taking a chance" (no-one really knows yet what reliability SpaceX can achieved for re-used first stages), one (or more likely one's insurer) probably would spend that extra. If it's Uncle Sam who's just spent $1billion make a new military satellite, $15million is really small beer indeed.
They will get to re-use one of their first stages one of these days, but the money saving isn't as attractive as all that to launch customers (or their insurers). If SpaceX can show that it works "as good as new", which I'm sure they'll manage to do one way or other, then it would become a no-brainer. But just at the moment it'd be a brave customer to bet their own enterprise on a small saving.