Those Lomo cameras aren't actually worth their prices, sorry to say. I love Diana but after taking pictures with Holga, I stayed with my better TLR for taking 6x6 pictures. (She's lovely to look at though.)
Don't know about vintage, but Anthropologie and b&h photo both sell Dianas.
i have the same one...my first results are disastrous.. :-( but check http://www.lomography.com/
have never tried this one