Depending on your lighting situation, liquid fertilizers may be called for. Under high light conditions, plants are driven harder, and require more nutrients and CO2.
If you are looking to save money, then you should purchase dry chemicals; it is the cheapest option, and you can customize your own dosing.
I have an eheim aquastyle 9 - the light from what I've gathered is medium, a 7 watt LED, supposedly 1200 lumens I think? And I hear that because it's LED light it cuts through water differently/more intensely than other types. I've heard it's medium to approaching high in terms of brightness but I can't tell myself since this is my' first planted tank. I don't think I can afford a CO2 setup anytime soon either btw. I could look into a DIY scenario later on at some point maybe but don't people do rather well without that anyway?