It depends on tent size but anything over $100 is going to work. Do not buy the ones that are $80 and smaller.
Look for the operating wattage. Anything that’s 200-500w is going to pull water at the right rate. If you have the right set up, I’d encourage you to get one that has a hose so you don’t have to empty the dehumidifier 2x a day. Also make sure you calculate tour wattage or buy a wattage meter so you can figure out if lights+dehu+everything else can run without tripping the circuit.
1500-3000sq ft around 30 pints per day works well for a 4x8 or smaller.
I’ve had good success with this one
Always make sure you cover the lights on the dehumidifier with tape so that it isn’t emitting a bunch of light at night during the dark period, although with autos that doesn’t matter.
This one is pretty low wattage so you probably don’t have to worry about using different circuits.
You're not going to find an air conditioner for less than $200, the very cheapest units they make start from at least $300, usually $400 on up. In your price range look into a dehumidifier, which produce warm dry air, rather than the cool dry air of a portable AC. If you do get a portable AC, make sure the model you're looking at can be run as a dehumidifier, some cannot.
Here is one of the most efficient small dehumidifiers on the market, it's $149.99 on Amazon. Being more efficient means it will cost less money to run and warm up your room less, but it will still produce heat. It's critical that you get a dehumidifier that has a compressor, the cheaper Peltier or TEC / Thermoelectric Cooler types don't really work.
This site lets you search for Energy Star certified dehumidifiers and sort by efficiency. As mentioned in another comment the "guts" of all these models come from the same factory in China, but some models are built using newer and more efficient technology. Efficiency means how much energy is used and thus how much heat is produced per pint of water taken out of the air. This is super important in a warmer season when you don't want things to feel muggy, but if things are cold and moist and the heat from the dehumidifier just means your heater runs less, maybe it doesn't matter. The most critical thing is that any dehumidifier you buy use an actual compressor, the thermoelectric/TEC/Peltier models only work in humid tropical climates .
For a bedroom or other small room, this 30 pint model looks to be the most efficient option. The 50 pint version is the same physical size and will just make more heat and require you to empty the bucket more often. There are more efficient options for the 50 pint and larger size, but the difference is small and they're hard to find.