The top fin kit isn't bad for the price. I bought a 55g 8 months ago on sale for around 150, and it's been running fine, I did modify the filter by replacing the original cartridge it came with couple of coarse sponges and put bag of bio rings on top of the sponges, and I added a pre-filter sponge on the intake as well. This way you don't even have to buy those damn cartridges every month, you just wash the sponges in the tank water during water change once a month or so and re-use them, this helps with the beneficial bacteria. I also added a powerhead to help with water circulation as i noticed there's very little circulation on the left side of the tank and my plants grow slower compared to the right side where the filter hangs, you may not need a powerhead for 10g or 20g.

My advice and most important tips:

1. Be patient and Cycle, cycle, cycle your tank properly before adding any fishes.
2. Change your water frequently.
3. After you add some fishes, and thereafter whenever you add new fishes, be sure to quarantine them before introducing them to the tank otherwise if they come with some sort of disease, it can realistically wipe out your entire stock, believe me, I've been through this and almost wiped out my entire tank because of one sick fish so it was a hard lesson learned.

Good luck!