Mini Nano Filter and Heating

#1
Okay can anyway give me some names of cheap but efficient sponge filters for a 1g? I dont want alot of flow due to it housing a betta and some plants but enough to maintain oxygen!

Also would a 25 watt heater work in a 1g or would I want to try to find smaller? I cant seem to find anything less than 25 watts but is there a place online that sells like a 5 watt heater for cheap?