Costs are far lower than you’d think. Used Adaptec SCSI Cards are about $10 on ebay. The right cable might set you back another $20 or so. That said I wouldn’t base my decision on cost.
I still deliver all of my projects on DLT as it’s a more reliable medium than a dvd-r (especially for DVD-9’s). I find that clients are far happier spending a little bit more on a few blank tapes up front, than running into an issue at replication.
*- blackbird digital studios
*- dvd design, editorial and production
*- marin county, california, usa
*- https://www.blackbird.tv