Yes, 500 quid will buy you a lot of turntable, especially second hand. In fact, I went digging to see what was available and I want a turntable again. Besides the obvious Rega and Project decks you can buy new for that money, there are some incredible bargains on the second hand market. A clearaudio solution with origin live arm - the second most beautiful turntable in the world - just went for 650 quid on eBay, which is amazing, I just sold my Project RPM5.2 for less than 250 quid, and the local hifi shop has a Rega P25 (kicks P3 butt) for 400 quid with a short warranty. So that gives you an idea of what's available within budget.
The phono stage on the Marantz is a good starting point, but obviously a better deck will benefit from a better phono stage in the fullness of time.