Here is a list of reported sales from the last 30 days of LLL .io domains:
hck.io 106 USD 2016-09-16 Flippa
gto.io 224 USD 2016-09-14 Park.io
lbc.io 100 USD 2016-09-14 Flippa
mpr.io 300 USD 2016-09-13 Flippa
tow.io 338 USD 2016-09-09 Flippa
dac.io 255 USD 2016-09-09 Park.io
svr.io 622 USD 2016-09-07 Park.io
ktm.io 106 USD 2016-09-05 Flippa
rea.io 3,200 USD 2016-08-31 Sedo
ucc.io 185 USD 2016-08-31 Park.io
zag.io 510 USD 2016-08-30 Park.io
pdt.io 104 USD 2016-08-30 Park.io
wil.io 104 USD 2016-08-30 Park.io
eci.io 106 USD 2016-08-29 Flippa
dix.io 104 USD 2016-08-28 Park.io
eos.io 185 USD 2016-08-26 Park.io
yug.io 104 USD 2016-08-26 Park.io
xoo.io 126 USD 2016-08-25 Park.io
lbc.io 196 USD 2016-08-24 Park.io
ead.io 150 USD 2016-08-24 Flippa
cul.io 104 USD 2016-08-19 Park.io
Maybe this will help you with the current value. Hard to tell the future value. Hard to tell by "random letters".