Changing the price from a competitive one to a hugely disproportionate one when a product is sold out is a common practice on sites like Ebay and Amazon - and now presumably Bestbuy.
You see the products on these sites are subject to a 'best match' algorithim which is based on the amount of clicks the product . If the product listing is withdrawn (due to it being sold out or unavailable), it receives no clicks and is consequently demoted in ranking when it is relisted (as the automated system assumes that rival, similar products are more popular).
The longer it is unavailable, the further it is demoted. This can lead to a loss of premium visibility when it does come into stock, for the reasons given above.
It seems weird, but it is sometimes better to keep the item listed at a ridiculously prohibitive price, than to remove it from search (particularly if the item was popular when it was available) so that it does not lose its ranking when it comes back into stock. As previously mentioned, this practice happens a lot on eBay and Amazon.