You're lucky they even counter offered. Most times you just don't hear from them again, at least until they are in a bind and really want the job done right.
In reality, the $$ per s/f is not really the main factor. The important thing is, can you make a decent living at a certain rate after factoring in expenses? With very large jobs, the answer is sometimes yes. With good chems, and the right equipment, it is surprising how many s/f per hour can really be done.
3 cents is on the low side, but 5 cents can be do-able, and still make satisfactory money. I think they will find that for the money they spent, they will not get a very good job done, and that may be alright with them.
I look at it this way.....when I'm busy and highly booked, my time is worth more. But during the slower seasons, when I may not have much work to do, I can afford to work for less as opposed to making nothing. It's just a matter of balancing out what work you have, and what you need to earn to provide a living.
Some may say not to offer services for a lower price, but in different geographic regions, competition may be fiercer, forcing us to work for less than we would like to.
That's not lowballing mind you, it's putting food on the table. I don't have another day job to fall back on, so if I were to always stick to my guns and say I'm not going to work for less than this or that, then my family is going to go hungry. That's the way the world is headed, and there's not a darn thing we can do about it.
My .02