Plate jointers are kept in the hand/power tool section - near the back wall.
#20 biscuits do a pretty good job of holding surfaces even, but you'd do just as well with a spline - or even clamp blocks top and bottom.
it you want to try for the spline, use your router to cut a stopped groove (1/8" wide by 3/8" deep) in the adjoining surfaces then use your table saw to cut the spline out of the edge of a 1x. (zero clearance insert on the table saw is your friend here)
of course, biscuits come in handy on other projects as well, so I'm not saying don't buy it, just if this is the only project planned for it, there are alternatives.