There are so many people in the computer publishing field looking for new niches to occupy that you have to stake your claim way before there is a real market for your paper if you want to steal a march: accordingly, the San Francisco-based publisher Coastal Associates Publishing Ltd Partnership is to offer NeXTWeek on the NeXT Inc machine, initially offering it as a quarterly supplement to MacWeek to make its marker for what could turn into a big new market: a price and feature comparison of NeXT, the Macintosh, an IBM PS/2 Model 80 and a Sun Microsystems Sparcstation 1 is the biggest come-on for the first issue; Coastal is is a limited partnership of Ziff Communications Co and Patch Communications.