Tektronix TDS500 and TDS700 series are easy to fix as long as there are no more than two errors in the startup screen and there is tons of information (including component level manuals) out there. ASIC failure is extremely uncommon in these scopes and the NVRAM can be fixed or replaced easely.
Yeah and if you can get one for <$150 who cares? If it does eventually have a terminal fault you can part it out and make your money back and then some.
I recently picked up a TDS784C, after buying new relays for the attenuators, a set of probes and some other bits and pieces I have about $800 invested but this is a 4 channel 1GHz 4GS/s color display scope loaded with all the options, deep memory, hard drive, advanced FFT, list price when new was over $35,000. It would cost me much more than I paid to get a modern instrument with equivalent capability.
This is academic though, as like I said, for a beginner I would recommend starting out with an analog scope, the exception being if you plan to work with digital circuitry where you need to view stuff like SPI and I2C busses and other non-repetitive stuff. That's where a DSO really shines, but the learning curve is a bit steeper and there are a few pitfalls. Analog scope feels more "real", it doesn't have that abstraction layer between you and the signal, if that makes sense.