PainiyffThe UD-501 released at a similar list price, it's now 5+ years old which is why you see it for less than half the original price. The 503 is being sold at a discount now that the new 505 line is out, this cycle will continue as long as new models are released in the same line. The $359 price was $500 off it's original selling price, this is $349 off it's $999 release price... this model will continue to drop in price until all stock is cleared out. It's part of the concept of the life cycle of a product and in no way unusual.
ElectronicVicesOf course it's not unusual for pricing to depreciate over time. However when my original comment was posted, the 503 was double the price of the 501 on massdrop, which is a much bigger difference than it is now and therefore imo not worth buying the 503 at the time.