Consumers who have been considering an upgrade to their PC or Mac’s RAM may want to make their purchase sooner rather than later. What began as a mild, but noticeable, uptick in RAM prices during the first three months of 2013 has expanded into shortages that several computer makers state could send prices even higher and hurt sales. For the past several years the price of computer memory fell considerably (reaching, as some pundits have said, “ridiculously low prices”), making…