I think the 's' greatly diminishes PrintPortals.com resale and development value. The 's' sounds forced and unnatural to me, compared to other possible non-plural alternatives that are probably out there for reasonable prices in the aftermarket, like PrintPort.com, PrintPoint.com, or even PrintPortal.com.
If you are asking because you are thinking about developing PrintPortals.com, I'd say save the money you'd spend having PrintPortals.com appraised and apply it towards acquiring a better domain.
If you are asking to know its resale value to a reseller or developer, the reality is that it is worth nil to nothing.
The best thing to do now is to cut your losses by not wasting anymore of your valuable time and money on what is, in my opinion, a majorly flawed domain.
To sum up, look for some greener pastures and forget about PrintPortals.com!
