If you are looking with sticking between the $300 to $400 range, then you should look at a 29 gallon aquarium. Here is a sample of your costs.
$40 | Your 29 gallon aquarium.
$25 | Filter for your aquarium
$30 | Aqueon Pro 150 watt heater
$30 | Gravel for your aquarium
$30 | API Freshwater Master Test Kit
$25 | Fake plants for your aquarium
$20 | Prime Water Clarifier
$3 | 5 Gallon Bucket
$15 | Aqueon Water Changer
$100 | Lighting along with covers
Total: $315.
You can spend money of fish after this,
I personally recommend 10 cardinal tetras. 1 dwarf gourami. 1 birstlenose pleco. 4 german blue rams.