I was in one of my favorite junk stores today and came across a Univex straight 8 cam I'm sure just like yours. I see that it takes 30' of film. You can just get a DR8 spool from John Schwind and split it in half and load it up. Also in the middle of the night last night not sleeping my wacky ADD brain remembered that there is indeed someone who sells straight 8 film:
Kahl.
http://www.kahlfilm.de In 10m lengths aka 30'. They're probably the only ones in the world at this time doing so. But it's good to know. they have both color and B&W. Here's a google translated excerpt:
Welcome to Kahl Film & TV
Filmmaterial Footage
Wir produzieren und vertreiben Filmmaterial der Formate 16 mm, Super 8, Einfach 8 (1 x 8 mm), Doppel 8 (2 x 8 mm), Doppel Super 8 (DS 8). We produce and distribute footage of the 16 mm formats, Super 8, single 8 (1 x 8 mm), Double 8 (2 x 8 mm), double Super 8 (DS 8).
They have Kahl UP24 ISO 200 B&W and UT18 Chrome ISO50. Which has received pretty good reviews.
It's very expensive however at E34.00 each including processing with a minimum order of two. But I think it comes with those super rare reels for the Univex. You should email them and ask. They will answer in english.
It may be worth the expense once just to have the extra reels.
Also if you're interested in the camera I took a picture of it. It only has one reel in it and the winding key is missing so I was unable to test it. Very cool little camera though. The dealer said he would sell it for $15 I think. Might be worth it just for the reel and spare parts.
Cheers,
James E. Stubbs
Consultant, Vagabond, Traveler.