not to sure what kind of fish i'm going to put in yet as we have a water softener here and my test kits are in the mail. after i can get the water parameters then i will decide fish. as far as plants go i plan to have a nice mix of low to mid light level plants, i havet done any research yet as im still getting all the equip together. gravel would be nice as you said byron but at the pet store you pay 4x as much just because it says aquarium on it. but who knows maybe i need to just stop being so concernd about price
and you are saying about 3 inches or so of substrate about how many lbs is that for a 55 gal thats 44inches long 13 wide?
Money
A caution on the water softener: many soften hard water through ion exchange which means removing calcium and magnesium ions by adding sodium ions. Sodium is salt, and many fish that would not do well in hard water (hence the softener) won't tolerate salt either, so they are no better off. Peat filtration and RO (reverse osmosis) are the best ways to soften water. I would go with RO water if it were me and I needed to [more on this momentarily], since peat has to be continually replaced (the tannins leech out and it becomes useless, in short order if the water is quite hard, and with a larger volume of water and weekly partial water changes...). With RO, you would treat some of the water and mix it with some untreated water to keep a bit of mineral and hardness; no fish can live in pure water that has no minerals or nutrients, like distilled water or full RO water.
Re the hardness, once you have your test kits and know how hard your water is, and the corresponding pH [they are linked due to the natural buffers in hard water that will prevent you lowering pH without altering the hardness, in simplistic terms], you can decide how to proceed. If you have very hard and alkaline (basic is now the term) water, livebearers and rift lake cichlids will be fine. If you decide you want soft and acidic water fish like SA tetras, dwarf cichlids, SE Asian fish that prefer (and some require) softer, slightly acidic water, you will know what will be involved to get it. On the other hand, you may already have water that is perfectly useable (maybe slightly basic, low 7's pH and moderate hardness) and no need to fiddle with it unless you intend getting into sensitive wild-caught acidic water fish like discus or something.
Re your plant thoughts, that is similar to what I have; you've probably checked my aquaria photos, and in both those tanks I had regular quartz aquarium gravel (it is inert), smallest grain size I could get, with Nutrafin's Plant-Gro sticks next to the largest swords that are heavy root feeders. Liquid fertilizer (Seachem's Flourish Comprehensive) twice a week, no CO2, and minimum light (one watt full spectrum per gallon) completes the picture, and I have no trouble with those plants thriving.
You can get gravel at some landscape places. Just make sure it is inert. Some (limestone, dolomite, coral, marble based) contains calcium and minerals that will raise pH and hardness. Quartz gravel is, as far as I know, inert unless something specific has been added. I purchased all my gravel (I have two colours, one in the 90g is gray/black base, one in the 70g is "natural" buff/brown base colour) from aquarium stores but in bulk which is considerably less expensive than prepared bags. Coated gravels can sometimes leech their coating (colour), I had this occur some years ago with some black gravel. Bulk gravel is the best in my view, just get the smallest grain size. A natural, darkish colour brings out the colours in fish and plants, and the fish feel more relaxed [I have evidence of this I won't go into here].
It used to be said a pound of gravel to a gallon of tank volume. I have so much gravel, bought years ago now, and keep moving some of it around as I change tanks, that I can't remember how much I bought for the tanks. But if you buy 60 pounds in bulk for your 55g tank, you will probably have enough and some to spare--and its handy to have spare, as you may decide to build up this or that section with a rock and the spare gravel gets used. I'm fairly certain I went with 60 pounds when I set up my 55g tank, but that was in the early 1980's so memory is a bit rusty, but I followed these generalities more back then.