[nindustrial]

Similar to what foghat suggested, check out my similar el-cheapo book-elastic-band 'solution'. Rather than a standard-fare rubber-band, why not one of those elastic-fabric bits easily available from any sewing/fabric type store? Choose your own colour that way!

Mine is a re-purposed elastic-fabric band lifted from an old used Moleskine-type notebook. With the standard Sony cover (no-light version), just place the elastic strip on the inside before snapping the reader into place; the felt 'cushion' in the case holds it tight enough against the Reader.

Another nice thing is that it loops around and can hold the cover-open against the back too. You may need to reposition to find the exact level of tautness you want.

I'm happy with it - inexpensive, and makes the cover-case so much more useful. It looks professional enough to me, like all things subjective to personal taste.