leon,
Using
ebay, I've bought, or bid on, a number of art bars, even a couple of yours, and in my experience, one can expect to pay at least $3-5 above spot for art bars of similar ages such as yours. Really, prices on many of these go WAY above what one pays for a silver eagle or maple, for instance. It all depends on rarity (of course). It's expensive and very hard to find but someone published a comprehensive art bar catalog in the 1990's called An Indexed Guide Book Of Silver Art Bars. If you saw the prices that some of these bars command, you'd probably be gobsmacked. Sadly, if they don't have a cash value attached to them, many coins snobs will disparage these as hardly worth the metal that's in them, but if one takes the time to look, there's a thriving niche market for art bars and rounds, even newer rounds like those produced by Zombucks and Silver Bullet Silver Shield. Personally, I like the variety one finds in art bars and rounds, and don't mind paying a premium for certain themes that appeal to my taste.