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Scopes vary in the input capacitance, I've seen 20pf to 50 pf or more. The input resistance should be the standard 1 M ohm. Make sure that the compensation adjustment on a 10X probe can cover you scope input capacitance. Some cheap 1X probes might add a lot of capacitance. I would think the cheap probes wouldn't be as durable. Some of the more expensive probes have accessory adapter tips, ie. different kinds of points or hooks.
For alignment you really don't have to have a very fancy scope. The scope is used in the X-Y mode (make sure the scope has that) and the horizontal sweep is only 50-60 Hz in most cases. You would want to use a demodulation probe or connect to the demodulation signal in the set, that means that the scope bandwidth can be very low (audio range). For TV work you can get by with as little as 5 MHz bandwidth since that is the bandwidth of the video. Looking at RF or IF you would use a demodulation probe, and in some cases a meter. A good scope will have a stable and reliable trigger circuit, I'm not sure a cheap scope would. Input sensitivity is another important spec.
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