Hi
have never bought on line though my 150 125,75 were used . got them from ads in the paper. I LIKE seeing what I'm buying lol. Have you checked around for prices so you'll know a bargain when you see one?? Keep in mind that irregular shapes(bowfronts ,Hexes are far more expensive then rectangles. and of course require specialized equipment. Also keep in mind that "equipment " can be 2/3 tiimes th value of the tank.
Have you a particular type setup in mind ?? Will go a long way in determining what type of equipment you'll need.
As to stands ,I generally make my own can be as cheap or expensive as you choose . Most commercial stands are made ffrom inferior materials IMO. If you opt for furniture grade keep in mind the cost will be 3/4 times the cost of a seviceable stand. One thing to avoid is "particle board". , even the very expensive ones are usually veneers over PB. The logic of making something out of a material that can't get wet escapes me.lol
As to pumps filters heaters and so on much depends on what the setup will be . Usually when you buy used the equipment comes with it so your stuck anyway?? lol
Good luck gary

I have been looking around, I see a lot of 55 gallons and 100 gallons, some 75. I know I want a 75, the 100 would be too big. Not sure what kind of set up I want, I assumed they were fresh or salt.

Hi
there are dozens of kinds of Fw setupslol. Hard/softwater,planted ,rocky ,Tropical temperate, Then there's the more exotic paludariums ripariums even aquatic terrestrials lol
There are even setups between SW/Fw called "brackish" differing by the amount of salt. There are even swamp or tidepool types. All depends on what you want to keep in the tank While most people keep either tropical or temperate fish there are gazillions of other choices lol
Obviously different types require various types of equipment. Seems like you have a "tropical community" in mind?? gary

I guess so, I suppose tropical is the most common newbie kind :) I'm thinking Cichlid's this time, but I have small kids and they may want the cheapies that you see at walmart. The neons and what not. My biggest issue is that the aquarium store is 1.5 hours from here. Not sure how easy is will be to transport fish from there to here, or if I need a supply fairly quickly - the internet or walmart/petsmart will have to do!!!

Hi
For tanks over 55 I'd recommend "African rift lake" cichlids. Very colorful and if fish have personalities they're among the top 10 lol kids will like them for that reason They do require "rocky" setups with high pH.
Do some research on the family as some are extremely aggressive. They are commonly available at chain pet/walmarts but are usually sold as "mixed chichlids" So you need your own knowledge of what your getting for sure.
They become VERY tame so the kids can help care for them.
They are mouth brooders and reproduce readily in an aquarium another plus for the kids??
Only negatives to them is that they are large, rip plants apart and some are extremely aggressive.
just takes some forethought in the original setup. gary

The standard sizes are by far the cheapest, the 55gal being the original big tank, and a good bargin. shop online at Foster Smith to get pricing ideas. good luck.

Just use coolers,try to get them home quick ,dont they say ok for about an hour in bag?

I had a 100 gallon acrylic. Scratching wasn't an issue, though I was careful. There are acrylic polishes that easily take out minor scratches. I gave it to a friend for his python. I have a 46 glass bow front now, no issues at all. If you run across an Eheim undertank (large) wet\dry canister filter snap it up. Mine's been running flawlessly for about 17 years, easy to service (doesn't need it that often), and uses only about 20 watts. It was pricey when I bought it, over $200, but worth every penny. I'd keep an eye on craigslist for a used one.