Nearly any decent 10x probe will work well on a 50MHz oscilloscope. Me, I prefer real Tektronix probes. These can be bought inexpensively; for example see
http://www.ebay.com/itm/Tektronix-P6...item4168a3deb7
On my Tek 475A I use P6063B probes (fast for this 350MHz scope), but also have a set of 100MHz probes (P6105) that work as well when I don't need the speed, or (for example) when I need a 3rd probe for a separate sync input.