I have a couple of the 555th jigs and these are pretty much the standard that people copied to make all others (exaduration I know). With the original 555th jig you need to take a little time and center your flats in the jig using a micrometer. It takes a little time but it isn't too hard.
The DPH jig is the first real imprvement but it is still esentially a 555th jig but they added locator pins that allow you to pretty much drop your flat over a couple pins and bolt ut up tight thus eliminating the measuring. Now, some people have added the alignment pins to their 555th jigs to do the same thing.
The AK-Builder jig is essentially the same as the DPH jig but it is shaped a little diferent so that the jig that you use to bend your flat will actually fit inside a second jig that will bend over the top rail.
Now, I can't really advise what prices are anymore or what the availablility but here are some links:
dpharms.com/now-in-stock-receiver-flat-bending-jig-p-115.htmlak-builder.com/ak/modules.php?name=Content&pa=showpage&pid=2I am reluctantly offering my jig (555th) for rent again if you may be interested...
www.quarterbore.net/forums/showthread.php?t=510Even with having to measure the flat to center it you can bend a flat in under an hour and the second and third flats can be done much faster... I am asking $20 + shipping to the next person but see the terms at the link as my last rotaion turned into a real hastle!