These ads pop up whenever you search for a brand or type of bike. Most bikes are pick up only, so it's a great bit of advertising. The prices look good too.
However, be very careful when picking a courier as most won't take a bike unless its completely wrapped, or in a box. Maybe not a problem for some, but the last thing you want is to pay for a courier and find this out when they go to pick up the bike you've just bought. Even though no mention is made of this in their listing.
If in doubt - check. Most have a contact number, all have the 'ask seller a question' button.