A few recommendations (to address your questions):
- Get a power rack, they aren't that expensive but they are very versatile. You can use them for squats, and as a personal spotter for bench presses. (bench sold separately). The lower cross bars are there to act as your spotter so you never have to drop the bar on the floor or worry about the bar pressing on your neck if you can't get a lift up. You also might be able to build one yourself if you are handy with wood and tools.
- Get Olympic bars, and keep an eye on the total load they can handle. Get one piece bars, there are a few cheap three piece models and I would not recommend them. 7' bars will be best.
- Check to make sure the Olympic bar is truly 45lb. Dick's Sporting Goods sells one they call an Olympic bar, but someone weighed it at 35lb. That's not Olympic bar specs.
You can get a starter set of weights with an Olympic bar and 300lbs (136kg) of weights for around $300 USD. The standard set includes:
- 2-45lb plates
- 2-35lb plates
- 4-10lb plates
- 2-5lb plates
- 2-2.5lb plates
Since my routine has me going up 5lb each time I workout (except for deadlifts, those are by 10lb) the 2.5lb plates are nice. When you are getting close to outgrowing the core set, you can buy 45lb plates separately and add them on as you need. That way you minimize your initial investment while still being able to work toward those 600lb deadlifts and 400lb squats.
RE: Calibrated vs. non-calibrated
A calibrated plate is certified to be the weight advertised on it. While a non-calibrated plate is not certified. It will likely be very close within a certain tolerance, but the calibrated plates are required for competitions. You can likely do what you need with uncalibrated plates.
RE: non-Olympic bars
Most non-Olympic bars I've seen have a smaller diameter (i.e. less than 2 inches) for the plates, and are also a lot flimsier. They simply can't hold the same amount of weight. While they are better than nothing, they aren't going to grow with you like an Olympic bar.