In the price range given, the DeWalt DW735 is a great bench top planer to consider and many of us, myself included, own and use one with plenty of positive reviews. It is the best of all the benchtop planers on the market today and has held that title for a number of years now. Even many who own large stationary planers will keep a benchtop planer on hand for final thicknessing when they want a smooth finish when making thin passes as benchtop units excel at this, their only drawback being that they remove less per pass and do not handle extremely rough cut lumber as well as a stationary unit.
The stationary planers can be nice if you routinely have to remove large volumes of wood or work with very rough cut lumber but they do not typically leave as smooth of a finish during the final finishing pass, particularly shallow passes, as their toothed feed rollers tend to leave an imprint on shallow passes versus the smooth feed rollers found in benchtop planers. However, as a small workshop you will likely want a bandsaw to resaw excessively thick lumber rather than just wastefully turning all that excessive thickness into wood chips as we can always find a use for the waste slices we remove on the bandsaw. For example, if I have a 4/4 (1") thick board and I need a 1/4" board I do not mill off 3/4" of material, rather I resaw it into a 3/8" thick board and a roughly 1/2" thick board and then mill the 3/8" board into a 1/4" board. Later the roughly 1/2" "waste" board can be flattened and milled into a board that is somewhere between 3/8" and 1/2" thick and saved for another project.
If you routinely work with highly figured woods (e.g birdseye, quilted, fiddleback, etc.) then you will want to consider a helical/spiral head cutterhead to reduce tear out, though that would be challenging to come by on a $500 budget. Fortunately, if most of your work consists of less wild grain pattern and more typical wood grains then the only major benefit of a helical/spiral cutterhead is quieter operation and straight knives do just fine. But they can really shine on highly figured wood with wild grain patterns since there is no optimal orientation in which to feed such boards into the planer.
With any thickness planer, consider adding a digital readout (Wixey) for greatly improved accuracy and repeatability. They really do come in very handy and make it trivial to dial in any thickness you want with perfect repeatability, give or take a few thousandths of an inch. They are also handy for occasions where you need to remove a very precise thickness from an already thicknessed piece (e.g. If your measurements show that a piece is precisely 0.015" too thick, you just use the relative thickness feature to shave off exactly 0.015", no math or guesswork required).
If you do not already have a good dust collector then be aware that such becomes very important when using a thickness planer so that waste chips do not get pressed into the freshly milled surface, scarring the newly prepared surface. The DW735 is one of the few that can be used without a dust collector (it has a built-in blower), but even it benefits greatly from a proper dust collector to keep the mess under control (and a mess it can be if DC is not available). A shop vac will not cut it as the volume of chips when thicknessing lumber can be extraordinary and even a proper DC waste bin must be carefully monitored and emptied regularly so that it does not overflow and clog the filters and impellers.
