you are going to be limited unless you find something used.
That prism makes a good door stop.
Some like Aqua C remora, some think they are junk.
Octopus seems to be liked and they make a good HOB for the price your looking at.
CPR Backpak seems to be a hit/miss altho the 2 chamber version does well.
Tunze is another liked skimmer.
Many think the Odyssea is junk, but I like mine.
Regardless which one you buy, new or used, they go thru a break-in period.
Running the skimmer in a vinegar solution can help reduce that time. Some break-in periods is short some can take a week or 2.
When you make adjustments, do so gradually and wait a few hours between adjustments. This allows the skimmer to settle into the new setting. Also, do not make a adjustment then go to sleep/work. Do so and dont be surprised if it overflows.
Also get a GFCI. Electricity aint no joke and you will have a lot of it around a lot of water. You can get a plug-in GFCI adapter at Lowes (or similar) for under $20