Avianca is back with it's 100% bonus offer for purchasing miles.
You can buy up to 75,000 miles which will translate into 150,000 miles after purchase. The price per mile will be 1.5 cent.
Avianca has a pretty reasonable award chart which looks similar to United or US Airways. Avianca charges no fuel surcharges.
Before you buy – look up your desired dates and routes at united.com. Avianca usually has access to the same flights you can see there.
Booking awards with Avianca can be a challenge as their online booking engine does not allow you to 'route manually'. You can only enter a destination pair and then select from the options it presents. The agents have a bit more flexibility but it's not as easy as with United/ US Airways where you can just read out each leg to the agent.
This can be a great offer if you are just starting out to collect miles. I purchased USAirways miles 18 months ago and was really happy about the first class flights I received instead of buying an Economy ticket for the same price.