A new DSO will have a warranty...
Yes, I think I mentioned this as an advantage of buying new.
A new 'scope with similar front end bandwidth and sample rate will be at least 5x the cost. Just looking at Farnell's web site a Hameg HMO3524 (350MHz, 4 channel, 4GS/s) is just shy of £4k ($6k) - OK, it's a hugely better 'scope and does have a 5-year warranty but if you can't afford $6k (I certainly couldn't) it's a non-starter.
For the same price as the Gould (about $900/£600) you are looking at perhaps a new Rigol DS1102D - 2 channels, 100MHz and 1GS/s, a nice 'scope by the look of it and the MSO capabilities and deeper sample memories are much better than the Gould. Not sure how much warranty Rigol gives you.
Whether that is the better 'scope to buy depends on what the OP needs - perhaps 400MHz bandwidth is merely a "nice to have" - chances are it is for a hobyist - but if its a "need to have" the Rigol won't cut it. I also don't know how easy (or expensive) Rigols are to get hold of in the Czech Republic.
At the end of the day, however, the question was "is the price reasonable" which it probably is given what else you can get hold of for that sort of money. Whether it's the
best buy is harder to answer.