RE: SANFORD'S INDELIBLE ink
I've seen the Sanford's sided, embossed on several of the sides (similar to the carters indelible), but not one embossed on shoulder and base. These little indelibles are really fun little inks, but never seem to generate all that much value. If amber of cobalt, maybe $50. The aquas seem to be available for about $30, IME. It may be because they are so small that, to show them off properly, you'd practically need a magnifying glass. Yours is a bit different, which helps a bit.
If you are interested in selling it at some point, pm me. I wouldn't mind adding it to my ink collection.