$300 and a 55g:
Depending on the deal you can find, I'd look at:
Eheim Pro III
Eheim Pro II 2026(better yet, 2028)
or, think about getting two Rena XP2(or two XP3).
The Rena XP3 is extremely comparable to the Eheim 2026. However, it's much much cheaper, and two filters is always better than one. However, one Rena XP3 would do well for you as well.
If you end up getting a Rena, you'll have money left over to buy whatever. I recommend looking at a Hydor inline heater, I think you would appreciate it.
Depending on the deal you can find, I'd look at:
Eheim Pro III
Eheim Pro II 2026(better yet, 2028)
or, think about getting two Rena XP2(or two XP3).
The Rena XP3 is extremely comparable to the Eheim 2026. However, it's much much cheaper, and two filters is always better than one. However, one Rena XP3 would do well for you as well.
If you end up getting a Rena, you'll have money left over to buy whatever. I recommend looking at a Hydor inline heater, I think you would appreciate it.