First of all, I wouldn't try to explain this to a client who has a poor understanding of the businss and what it takes to get a decent product. And as a disclaimer I have heard some stuff recorded in a garage with a handfull of 57's on a Mackie that stood up to most modern stuff these days (a tribute to the guy who did it). But here's one approach:
3 weeks at



studios $52,500.00
3 weeks with

tracking and mixing your album $31,500.00
3 weeks with

producing your album $42,000.00
Having

master your album $25,000.00
Having to recoup all this and more before making a dime
Not making excuses why your album sounds like a demo

PRICELESS!