Good Day,
I have been using AWS quite a bit for my cloud based system for a hardware project. Using SimpleDB and the notification service provided is great.
Nginix has an Amazon image that will load balance UDP for $2,500/yr or you can launch your own EC2 instance and use open source Nginx.
My specific use case was for a UDP logging service, if you can use hostnames Route 53 could be a scalable managed solution as well.