Looks like Flippa is currently down. Here is what you get when you goto Flippa.com right now :
Flippa is currently unavailable due to planned maintenance
All active auctions will be automatically extended for the length of time that the site is down.
Any issues, please contact Support.
Apparently its not due to planned maintenance as there tweet 21 minutes ago says this:
We’re currently experiencing some technical difficulties, we’ll be back to normal shortly with all auctions extended for any downtime.