Buff boots of mobility
Right now (patch 6.3+ ),
or
are better choose than 
for support.
It was designed to be the cheapest boot tier 2 in the game.
With 
for jungle , 
for apc , 
for adc, 
for top,
which all provide %mvt speed it become more and more difficult to flee as a squishy support .
my suggestion :
- 750po
- 30 flat ms passive: retreat : moving in opposite direction of nearest enemy grant +20 ms.(range 600) passive: _wanderer _: Increases to +70 flat movement speed when out-of-combat. Receiving damage, dealing damage or debuffing units will put you in-combat, disabling this passive for 5 seconds.