They're all the same really. The one without flash I like because I can put any flash I want to on it. Except those nifty Canon Speedlites. I thought mine was going to explode on it, well it did. Internally.
Did anyone buy one on ebay?
Are there things you have to pay special attention to when buying one?
( can you get them in an usual camera store?)
I bought mine on eBay. It's usually cheaper than most places you can find them (unless you find one used at a camera shop). Normal camera stores don't typically sell Holga's. Perhaps if you can find a camera store near a university campus, they might have some.
Just don't buy from places like Urban Outfitters! They overcharge you! All you really need is the Holga camera, not all the bells and whistle kits that places like Urban Outfitters sell that have "extra" stuff. Chances are, you won't use it.
Canon 8600. I have the model before, the 8400F. Easy to use, at first. Then when you want to get complicated, it's gets down and dirty. You can also scan past the frame, unlike other scanners. I can lay whatever I want on the glass and it scans without issues.