The presser foot you need depends on what kind of quilting you are planning to do. It is necessary to have a free motion quilting foot only if you are planning on doing free motion quilting. You can use a regular presser foot to do straight lines, especially if you are not working on a full-size quilt. For a straight or gently curving lines on a large quilt, you probably want to get a walking foot.
Here is a reliable source for parts:
http://www.sewingpartsonline.com/Sin...ine-Parts.aspx
It looks as if your Singer 2662 is a standard low-shank machine. You can check by referencing this website:
http://www.anniescatalog.com/pages/which_foot.html
If it's low shank, this means that you can use generic low-shank presser feet. (If you have the adapter, you can use Singer clip-on feet.) These feet are widely available. You usually want to buy an all-metal foot, as it is likely to last longer than plastic. Here is a link to an all-metal free motion foot on Amazon:
http://www.amazon.com/Distinctive-Da...dp/B007AUZ2H4/
Once you know what kind of shank your sewing machine takes, you can see all the kinds of presser feet available here:
http://www.sewingpartsonline.com/sew...sser-feet.aspx