I’ve been doing installs for a few months now for clients. Have now done simple installs, multisite installs, and installs alongside php/html5 sites.
$20 single discourse install
$25 multisite (multiple web containers one data container)
$30 discourse with reverse proxy and LAMP or LEMP
$35 multisite discourse with reverse proxy and LAMP or LEMP
requirements
Clean Ubuntu 14.04LTS 64bit install
1GB+ memory single install
2GB+ multisite, reverse proxy, and both
VPS/DEDI with kernel 3.13+ (no openvz)
ssh access
domain with A-record pointing to IP of install.
I am proficient with all of these installs now. After ssh creds are acquired, work can be expected to complete within the hour.
I don’t know anything about average prices; aren’t your prices way too cheap? Even when multiplying by 10, that still would look like a fair deal to me.