Check these out. This looks to be a bit like what you're going for so I would see what you can use from these videos.
As far as co2, if you are somewhat decent at plumbing then you can get some stuff fairly economical. Then, if you are able to hook up a paintball co2 cylinder to your setup, you can get a 20oz cylinder for about $30 and have it refilled at some sporting goods stores (like Dicks) or a nearby paintball field for about $5-7.
My tank is carpeted with staurogyne repens and no CO2. Fairly easy to grow, just make sure your tank is FULLY cycled before planting, or it will melt. If you do go the CO2 route, make sure it is off at night, or you could suffocate your fish. Also cichlids love to dig in substrate and may not be compatible with your plants. You might consider 30-40 cardinal tetras. They are beautiful in large schools. for clean-up, a bristlenose pleco or two, otos, shrimp and nerite snails. Good luck
The plants will probably not die off if you fertilize them. Honestly, I think you are en route to the number one planted tank mistake. Too much light. You want carpeting plants, carpeting plants need higher light, so you are going with two fixtures. Having that much light and no co2 will make your plants look kind of crappy. So you will start dosing nutirents. High light plus nutrients will equal horrid algae outbreaks. So then you try to fight it by removing nutirents, causing an even greater imbalance and more algae. I've seen many many people do this.Iv seen those vids, love the king (just watched his latest vid of his new "fish") I think I'm gonna try without co2 for a bit, worst comes to worse it starts to die off and I try co2
Personally, I am in the mindset of setting myself up for success, not "hope for the best". And I would bet that you could fit co2 into your budget if you managed to save money elsewhere. For instance, why spend 30 dollars a bag for "planted tank" substrate when you can use normal sand or blasting media for 8 dollars a bag and add diy root tabs for less than 20 dollars. One batch of diy root tabs will last year's. There's some money to be saved in lighting as well. Rather than go with 2 sort of ok led fixtures (the basic marineland strips really aren't that good) you could go with a t5ho high bay light from home Depot such as this:
http://m.homedepot.com/p/Lithonia-L...put-Fluorescent-High-Bay-IBC-454-MV/202838871
This will save money initially, put out more light, and be much more customizable than the marineland lights. Hope some of this helps.
This was going to be another suggestion of mine. I'm also doing s. repens in a no co2 tank with low light.
I've grown both S. repens and Monte Carlo carpets without co2. Excel helps, but you've got to be patient. It's gonna take a lot longer for you to see a nice lush carpet without co2.
Important not to mix with plants that prefer higher light. Along with the S. Repens, I have 3 varieties of java fern ( standard, narrowleaf and trifolia ) and 3 varieties of anubias (barteri, nana and fraseri) The tank was set up about 7 months ago and is doing well. At this point the only occupants are an irritans piranha, a bristle nose pleco, an undetermined number of ghost shrimp and some nerite snails. I plan to add a couple of more bristlenose plecos when I can find some large enough to fend off the piranha.
As others have said staurogyne repens is likely to be a good choice. Pogostemon helferi is another low growing plant that I have found to be relatively easy to grow. Slower growing than the repents though.
I have helferi in my high tech tank. Excellent plant. I'll have to try a bit in my low tech tank to see if it grows well.
