Why dont you just white SEo and social your sites to get good traffic and to raise slowly but constantly on alexa ?
Cheapest Alexa website traffic to get higher rank is at megasity dot com. This is the cheapest Alexa traffic worldwide.
Just be aware that most sellers of "Alexa Traffic" use a bot network software application called Jingling Flow Spirit. It's a Chinese software that is capable of random page visitation and custom set referral urls to make it look like legit visitors.