+1 Keen Shortsword (8,310 gold), for a basic weapon.
Boots of Striding and Springing (5,500 gold) to further increase your movement options.
Ring of Force Shield (8,500 gp) to give you some extra protection
Ring of Protection +2 (8,000 gp) to give you more protection
Cloak of Resistance +2 (4,000 gp) to help your saves
Add in the 12,500 you've already spent, and you'll be at 46,810 gp spent, which leaves 3,190 gold. You'll want your basic equipment, obviously. I would also recommend picking up a fair selection and amount of poisons. If you have enough left over after all that (and some potions), consier a Heward's Handy Haversack (at 2,000 gp) - you're strong and don't wear armor, so it isn't stricly neccessary, but it would be helpful for organizing things and hauling treasure out.
You could also drop the protection on the ring or the cloak, and switch over to an assassin's dagger (or see if you can get the same benefit on a shortsword).