According to this report:
After tumbling for more than four consecutive months, prices on dynamic random access memory (DRAM) may sustain rapid decrease in the coming months, causing memory chip makers to continue losing money. Nevertheless, as the demand towards computers increases in the second half of the year, towards back-to-school season, the prices may start to rebound, according to DRAMeXchange.
Price of one 512Mb DDR2 PC2-5300 (667MHz) chip has decreased by 53% in the last twelve months from $5.21 to $2.37
So, for the next couple months, DRAM should be much cheaper (around 50% cheaper) than it’s been for a while but it’s expected to bounce back up in a couple months – so keep an eye on RAM and upgrade before July or so! With 512 meg chips being 50% cheaper, you could add a gig of RAM to your computer for the cost of half a gig – nothing makes a computer run better like more RAM! 
