Sun Microsystems Inc yesterday responded to IBM’s Personal System/2 and DEC’s VAXstation 2000 by slashing the entry price on the 68020-based Sun-3-50M 36.8% to $4,995. That buys 4Mb processor, 1,152 by 900 pixel 19 mono monitor, Ethernet interface and Unix System V. The 68881 co-processor falls 43% to $400, and-on memory by 33% and on-site maintenance is cut up to 50%.