unfortunately, i haven't ever seen any lower than $600. nothing lower than the prices you mentioned lately. they are already priced really low for a quality 1911. that's probably why you can't find them cheaper. i only expect costs on them to rise.
that being said, i had mine out yesterday again. we had a couple of additional shooters with us (neighbors of a buddy). both were thrilled to death with the spartan v. when i handed it to the first guy, he did a double take and was very surprised to see the 9mm. he didn't realize there was another option than the EMP in 9mm. he loved the spartan. as he handed it back to me he said, "i WILL have one of these."
on a only slightly related note, thanks to those two shooters i have now had a chance to shoot both the ruger sr9c and the sprinfield xds. both impressed me. the ruger was extremely fast to acquire and reacquire a target after firing. very very accurate. i would dub it the bargain of the stingy gun buyer. at $400, you get much more than you pay for. the xds surprised me with its lack of recoil. i compared it side by side with my pps, and it is identical in size. even in 45, there was less felt recoil and definitely lower muzzle flip than my pps. i even had the medium mag in the pps and the flush fit mag in the xds. as i handed it back to him, i quoted the other guy and said, "i WILL have one of these."
Favorite range gun for the money - CZ 75B or STI Spartan V 9mm
Go-to carry setup - Walther PPS or PPQ in FIST kydex holster 1AK
Favorite semi-auto design - HK P7
"A Sig is like a lightsaber - not as clumsy or random as a Glock."