For example: sometimes (not always) I can "rush" a piece... but since that requires me to work extra hours, it does cost extra over my regular price, since I need to do extra work to fit it in. Similarly, sometimes I can work the materials so they are less expensive than they would ordinarily be... but this generally takes extra time to manage. And at any point, either of these may not be possible; it depends on the current circumstances.
So: trying to low-ball both the price (which I set fairly, based on what your piece would cost to make) AND the deadline is not a win. I know there's a lot of stuff being published that says that one should negotiate EVERYTHING. Sometimes, though- that's not true.
I offer excellent work for fair prices (actually, my prices are currently rather cheap based on various pricing strategies). I know this. I also know how long things take me to make, including my current queue of commissions. Trying to finess one or the other- well, it's a trade-off, and might or might not be possible; trying to finesse BOTH- no. I can't do it. Period.
If you are commissioning something from an artisan, please think about giving them credit for knowing their own work, and offering a fair price. If that price is more than fits your budget- unfortunate; I think we all understand that! Gods know I soften at the sight of some stuff I can't afford! But- I don't expect that makers of such things will discount their work to meet my budget, because I know they can't afford to- and neither can I.