The genuine Singer walking feet are less expensive.
Here's one:
http://www.ebay.com/itm/Singer-Smoot...item20dbb41843
Another, in the box:
http://www.ebay.com/itm/NEW-SINGER-S...item2ecc3795e2
Just search
Singer even feed.
For the FW Sew-classic has one for straight stitch machines (ones meant for ZZ machines don't work as well)
http://shop.sew-classic.com/Low-Shan...tch-P60400.htm
She also has an inexpensive Singer slant walking foot:
http://shop.sew-classic.com/Singer-S...t-421333-S.htm