If the price of the higher end DLT is a problem, consider the DLT VS160 (80/160gb) or DLT V4 (160/320gb). Those two drives should be cheeper then a full SuperDLT tape system, but is still built on the DLT tech.

LTO is also nice, but it usually is even more expensive then DLT. Reason being, LTO is a similar tech to DLT, but adds a RFID chip in the tape to store the catalog, allowing for faster file access. AIT does the same thing, where it adds a similar chip to DAT tapes.