If I ask the client between shipping a bug now and then and developing twice as slow, I know what he'll tell me.
(edit: twice as slow is about the same as twice as expensive)
Shipping bugs is not a show stopper. It's not even serious. What is serious is developing a live, production app without any consideration for bugs: backups (at least a couple of very different kinds) and control keys. A control key can be anything which will be visibly not ok when there's a bug somewhere.
I do management apps with a web interface: pretty flat architecture, no OOP to speak of, low complexity except the occasional long database query. So bug fixing is not really that time consuming, and definitely not the kind that would be caught by tests. Lately most time has been wasted on configuration issues of one kind or the other.
(edit: twice as slow is about the same as twice as expensive)
Shipping bugs is not a show stopper. It's not even serious. What is serious is developing a live, production app without any consideration for bugs: backups (at least a couple of very different kinds) and control keys. A control key can be anything which will be visibly not ok when there's a bug somewhere.