Not at all. For most situations your approach is the better one. Just a few situations where there are exceptions.
For most of the folks on this forum (microprocessor focused with fairly low speed analog signals) I personally think that the Rigol (purchased new) would be a better investment than a used analog scope from one of the big names. I have purchase more than one used analog scope that had significant issues, not the least of which is poor/no calibration. So I am not sure beginners (at least for this forums focus) are well served by used oscilloscopes of any kind-at least without a local Elmer they can rely on. 
BTW, How is your seismograph project coming? I am looking forward to seeing a write-up about it.