I just got a bench top planer but I am without a bench. As the planer is very heavy and I don't want to kill myself every time I go to use it I decided to place it on rollers. The easiest and most economical solution I came up with was using a small moving dolly that I got for $6, a piece of 2x4 from a pallet and several bolts. This also made unpacking it very easy for me to do alone.
Step 1: Flip the Planer Upside Down
Step 2: Check the Fit
Measure the base of the planer then cut the 2x4 to length and then lay it out and clamp it.
Once flipped remove clamps and apply bolts and you can use the clamps as breaks. Is this as good as bolting it to a bench and having appropriate height extensions, of course not but a cheap solution for a cheap planer.