Question : Problem: apache log archival/backup solution 1.5TB a month

We create about 50GB(1.5TB) a month of apache logs that need to be archived. Cost is  an issue. I am looking for an appliance similar to datadomain. Im open to all ideas though.

Answer : Problem: apache log archival/backup solution 1.5TB a month

DataDomain appliance are valuable if you expect many file duplicates...I don't see how to expect any gain from that using log files...

For a long term project where up to 15 years archive are considered, tapes stays the less expensive and best efficient way to archive files.
I would invest in a LTO-3 (400GB) or LTO-4 (800GB) tape drive (Only SAS or SCSI).

LTO-3 drive starts at $1.3k with tapes at $40 each
LTO-4 at $2.3k with tapes at $60 each

I hope your 50GB per day was WITHOUT compression.
You may compress (zip) your logs before archiving to tapes or try the tape drive internal compression...but usually software compression is more efficient.