Well, you may have a harder time buying something new like that from Tektronix. I've not worked for them since 1982 and don't know what's in their current product line for calibration equipment. The "original" amplitude calibrator was their 067-0502-00 and 067-0502-01 amplitude calibrator which was replaced by the TM500-series plug-in, the PG506. Then there is the newer CG5001, a TM5000-series plug-in which covers even more bases. Check out ebay for the earlier models as the newer stuff may get pretty pricey.
For that matter, an old Tektronix 500-series oscilloscope such as the 545, 545A, 545B, 547, 535, 535A, etc. has a calibrator built in that does most of what the 067-0502-01 amplitude calibrator did, just not as accurately. Of course, that's a pretty danged big box for just the calibrator!
Dean