Long domains seem to sell at desperately low prices, even for very common and desirable words (see below)
I also checked a database of companies and almost all those that have an .io have short names (5-10 characters mostly)
May be it can be a long term investment
Columns in the 'spreadsheet' below:
domain
Google monthly search
CPC (cost per click)
Transaction price
Date of transaction
Data from namebio
mobileapplications.io 720 1091 200 5/5/2015
affiliateprograms.io 8100 467 199 8/26/2015
healthinsurance.io 201000 639 180 7/31/2015
graphicdesigner.io 14800 834 315 6/2/2015
designerclothes.io 4400 172 105 2/18/2015
footballscores.io 246000 303 200 4/18/2015
nanotechnology.io 8100 180 150 1/24/2015
sslcertificate.io 33100 2323 201 2/9/2016
appdevelopment.io 8100 3444 175 12/19/2015
cheapinsurance.io 33100 2730 150 6/12/2016
homeinsurance.io 36 3038 151 7/16/2016
onlinecourses.io 14800 3192 295 7/19/2015
onlinetrading.io 8100 2071 110 9/28/2015
onlinebanking.io 27100 1048 132 5/13/2015
homeinsurance.io 40500 3253 151 7/16/2016
downloadmusic.io 74000 91 141 1/19/2016
unitedkingdom.io 74000 113 105 1/22/2015
dataanalytics.io 14800 3421 201 4/23/2015
bestpractices.io 9900 1634 109 3/23/2016
onlinedating.io 40500 595 105 1/21/2015
forextrading.io 12100 1466 180 4/5/2015
coloringbook.io 9900 53 350 6/17/2016
cheaptickets.io 1220000 168 100 4/13/2015
forextrading.io 12100 1466 310 3/13/2015
mobilephones.io 4400 468 174 1/10/2016
mortgageloan.io 5400 2331 178 8/6/2015
crowdfunding.io -1 -1 510 12/30/2014
onlinedating.io 1 5 105 1/21/2015
storagecloud.io 260 2113 151 4/18/2016
mobilephones.io 4400 468 300 5/12/2015
studentloans.io 165000 4081 129 3/12/2015
onlinepoker.io 27100 143 160 11/27/2007
stockbroker.io 14800 1952 200 1/2/2015
stockbroker.io 14800 1952 100 6/16/2015
dropcatcher.io -1 -1 250 9/6/2015
stockquotes.io 135000 111 100 8/29/2015
funnyvideos.io 301000 124 375 6/11/2015
domainnames.io 60500 1331 1600 5/4/2016
freewebsite.io 49500 1210 205 4/23/2015
creditcheck.io 27100 1708 150 2/25/2015
bodybuilder.io 0 87 155 4/15/2015
landscaping.io 720 312 448 7/21/2016
bestdomains.io 260 777 110 6/2/2015
screensaver.io 22200 57 115 7/23/2016
domainnames.io 60500 1331 1550 5/17/2016
liposuction.io 1300 710 205 1/18/2016
onlinepoker.io 27100 143 130 12/10/2014
refinancing.io 50 3003 430 5/12/2016
hotelsearch.io 9900 268 200 5/16/2015
outsourcing.io 320 5 499 2/17/2015
newyorkcity.io 1600 242 101 3/24/2015
greenenergy.io 5400 812 181 6/12/2016
luxuryhomes.io 12100 330 300 2/2/2015
playstation.io 40500 75 135 4/27/2016
photobooks.io 27100 612 120 3/20/2015
topdomains.io 70 1367 250 9/27/2015
vpshosting.io 5400 1661 105 5/20/2016
timesheets.io 4400 413 175 5/13/2015
chalkboard.io 8100 190 109 4/23/2015
domainname.io 60500 1331 425 8/12/2015
onlineshop.io 2900 317 150 4/6/2015
whitelabel.io 6600 809 2500 10/21/2015
photostock.io 2400 1263 116 12/6/2015
shortcodes.io 480 262 306 4/20/2015
debitcards.io 3600 992 120 7/30/2016
photostock.io 2400 1263 255 1/21/2016
losangeles.io 368000 409 1000 3/2/2016
forexrobot.io 590 341 145 5/26/2015
javascript.io 135000 50 2030 10/9/2015
itservices.io 18100 2034 100 7/31/2015
getstarted.io 2400 197 200 8/22/2015
remortgage.io 880 681 125 9/28/2015
datamining.io 90500 657 128 4/2/2015