There are many online clipart services that provide excellent clipart for rubber stamping; the best images are from services that are subscription based that charge a yearly or per image fee. If this does not suit and you really want to save money you should find out which service your rubber stamp manufacturer belongs to, it costs nothing to search through the clipart service that he belongs to as he will be the person downloading the images. This bit of lateral thinking and finding the right manufacturer will save you lots of money because you will never have to pay for the clipart. Clipart.com is one of the best services that some manufacturers subscribe to; I estimate that over 3 million images at Clipart.com are suitable for stamp production and they are fine with manufacturers using the images for rubber stamps.
For example, a parent might include the image of a Baby Jesus on each of the items that will be covered in December or a Easter bunny on items to be covered in Spring. Parents may use blank labels and print our their own custom stickers for this purpose using any of the free LDS clipart resources online.
Some designers actually make their available online in its original format, so that you can download it and make some changes, as well as resize it, though most will only supply a high resolution version that can be used up to a certain size poster. A Google search for.svg clip art will give you vector art you can use in Inkscape, and in fact some of it is exceptional.