Benchamrking and Progress Monitoring

We are working on implementing RtI in our Elementary school, as stated in earlier posts. We are currently using EasyCBM (the paid version). We have all the probes for benchmarking and progress monitoring that we want. However we have seen some of the reports that AimsWEB offers. We know the cost is qutie a bit more. Does anyone have input that may have used either or both? Is using AimsWEB worth the extra cost? Is there another program out there we could use, with a little less money? Thanks.