The tech companies listed here are all investing heavily in artificial intelligence. Want to add some promising artificial intelligence (AI) stocks to your portfolio, without paying an obscene price? Three AI stocks that possess a lot of upside and are among the cheapest options for growth investors to buy right now are Alphabet (NASDAQ: GOOG)(NASDAQ: GOOGL), Alibaba Group Holdings (NYSE: BABA), and Advanced Micro Devices (NASDAQ: AMD).