And by the way, no one's mentioned it yet, but fertilizers are actually quite cheap. I used to go the entire Flourish route: Trace, Iron, Potassium, Flourish, etc. Admittedly, that was at the beginning of my planted career and I had money to burn. However, if you take a look at the stickies at the top of this forum, you'll see that ferts can be had for quite a bit less than you'd pay Seachem for... especially traces/iron. I won't go into detail here about what common and obtainable chemicals equal what fertilizers, but the info is here in this forum.
I say this mostly because you said you were only going to fertilize for a month. You'll need to do it as long as you keep the plants, but it can be very cheap. For instance, I am running a 240G-4.75WPG-CO2injection tank. It may seem big, but I pay less than a three dollars a day for ferts and electricity for all (4! of) my tanks combined.