IMHO, that seller's asking price is overly optimistic. That said, a seller can ask whatever he wants, and there are buyers of whom cost matters little. This U.S. Mint medal is a very desirable design with an artful rendition of Lincoln. It has cross-appeal for collectors of both Mint medals and Lincolniana. Condition is extremely important. If your medal looks as good as this one, you may want to get it certified. Aluminum was a valuable metal in the 1800's. I'd rank aluminum as a less desirable base metal though, but that speaks to personal taste. You might try searching Stack's or Presidential's auction archives to perhaps locate the sale of this "King 518" / "Julian PR-12". My personal guesstimate for an XF-AU aluminum piece would be $150-$250.