There isn't too much you can do besides a salvage yard unit. If the dealer is quoting you $1400 for the entire Master Cylinder assembly with pump, solenoid pack, master cylinder portion, and ABS module; that's pricey but that's a pretty good deal since some members are getting closer to $2000 quoted for the entire assembly.
There isn't a rebuild kit as far as I am aware of, there was one "member" who commented in a thread a long time ago that their company rebuilt them. But they never replied to my inquires or posted any information, so I would guess they're a shady non-official vendor trolling forums. Nor are you really going to find anything much cheaper than $400 or so as it is unfortunately an expensive part. I do recommend you find a shop that has a Toyota compliant scantool should you decide not to have the dealer do the labor as you do need to have the system bled with a scantool after installing for proper operation.
Post Note-
I have tried the whole "rebuilding" (I use that loosely for reasons you'll see soon) when I sold my old unit to a co-worker. Turns out the unit sat a bit long in my cabinet (about 2 years or so) without much fluid in it and the master cylinder o-rings/seals dried up a bit (that was my fault, hind sight being 20/20) so I had to cannibalize the failed pump off his 4Runner and the one I had into a functional unit. I got lucky since his was strictly a failure of the pump/accumulator and did not have any failures in his master cylinder portion or in the solenoid pack. Long story short, while it is possible to sort of "rebuild" or cannibalize one or more, I highly discourage it unless you're really familiar with the system and your diagnostics are spot-on because you'll be taking apart the unit multiple times and swapping bits back and forth to get it working right otherwise.
