A Canon Scoopic M/MS is probably a better bet for a starter camera, even given it's limitation of having a permanent lens. It's easier to load than even a Bolex, it's motorized w/ multiple speeds, has behind the lens filters and a sharp fast 6-1 zoom lens Macro lens capability. Also, 400ft magazine adaptors usually turn up on Ebay for around $250-$300 every 3-4 months and 9.5mm wide angle lens attachments turn up every 9 months. I shot a whole feature on one and it has got to be the most idiot-proof camera on the planet. Scoopics turn up on Ebay at least once a month and it's posible to get one for $200 to $500 plus the sellers are usually in the USA. Often the batteries are duds, but you can get a scoopic to XLR cable for around $70 and I've seen instructions on how to make your own battery pack that you can load w/ either standard AA batteries or NiMH batteries. (Btw you should avoid the early Scoopic models-- the ones w/o M or MS; I've heard bad things.)
I've never worked w/ a K3 but I have a friend who does and he says it's okay; he's not crazy about the Meteor lens though and not having filters behind the lens can be a real pain.. I'd be interested to use one as a danger camera and it's nice that it can be easily upgraded to S16 for $375 (if you include having the viewfinder adjusted).
At the moment, I have an S16 EBM and man, the learning curve was steeeeeep.