Hi Rayston,
The plant package seems like a reasonable price for all those plants. For CO2 injection, the DIY method should suffice, but it may be a good idea to hook up at least two 2-liter bottles for a 55 gallon. As for lighting, you should have about 2.3wpg with that fixture which should be good for most of the plants that are in the package. Some plants like the Sagittaria subulata may require higher lighting however.
I only recently got into planted tanks so take my comments lightly, just trying to help out.
Toshi
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