It could just be supply and demand. More of one thing and less of the other will affect prices.

GPU cards might go through all sorts of different paths to travel from ASUS to your vendor. Different logistics, different economies, different distribution channels, different middlemen. Different "bottom-line" and "marked up" per-unit pricetags.

The prices you see online are not always the same as the prices you'll actually pay at point of purchase. Prices can change multiple times daily (typically in response to prices set by other vendors) while webpages might be duplicated or cached or updated with less frequency.

Ever-increasing silicon yields and refinements mean that, over time, more GPU ASICs (and memories) become available which can attain and sustain higher overclock speeds, thus more and more faster factory-overclocked GPU cards (along with their beefier VRMs, "improved" coolers, brand styling, etc) become available - sometimes at lower cost. Vendors often insist on selling off their existing stock of older-and-slower cards at greedily-fixed pricepoints ... but don't worry, they always eventually figure out that nobody wants to buy this stuff anymore unless they put it on sale at a loss.

If a faster and better GPU cards costs less then by all means buy it, lol.

You can't really make much of a definitive statement about a particular model, series, or brand based on only a single comparison between a couple models (or even a couple particular pieces). Every new GPU version is a completely different beast, every new subversion or variant is a similar yet still substantially different beast. The comparative merits of a brand can really only be judged when they consistently put out cards that are far above or far below the qualities and performances of their competitors. Not all songs by one band are great, not all GPU cards by one brand are great, even when some are consistently better or more popular than others.