This isn't exactly true when you're pricing items in crypto, which I assume a majority of miners do.  Not to mention Nvidia's 4xxx line is right around the corner and current mining profitability has USD prices the lowest they've been in years. 

I guess to answer your question it depends on what you're spending.  If you're spending BTC that you've held since the peak, it might not be the wisest idea.  However, if you're spending fiat that you've got burning a hole in your pocket, it's probably not a bad idea to start grabbing a GPU here or there if you live somewhere that you don't have to pay to keep them cool.