Source for tapes?

One of my clients needs new tapes for a Tandberg TDC3720. I think the format is called QIC or mini QIC. They're about the size of a Travan tape, but almost perfectly rectangular.
The tapes they have are labelled Sony QWX 3210XL. The only ones I have found around here are 20 or 40 MB.....that's right, MB. I need at least 1GB.

I'll look around the web, but if anyone can suggest a vendor, I'd be thankful.

I was able to find this about TANDBERG DATA. Unfortunately, it doesn't list your model 3720...it lists 3820s...is this your model number? Looks like 525MB is as large as it gets for this model...

Sorry I couldn't help out more. Let us know how it all ends up...Good Luck!