Stay away from Lubitel, unless you want the worst of the "Lomo-esque" results of blur, missed focus, heavy vignetting and washed out results. The above are good qualities sometimes, but Lubitel is a rubbish camera.
For the same price (thanks to Lomography "aficionados") you can buy decent German twin-lens equipment or Japanese, something Rollei or Yashica, or even Chinese Seagull.
For SLR Maymia and Bronica go cheap often.
My own entry into serious 6x6 (after rare use of lo-fi stuff like Holga and a couple of forgot-the-name cameras) has been not so lo-fi - got a black Hassie 500 c/m. They do not need further explanation - results are as good as they say and damn hard to beat in mid-format world. Zeiss lenses, 'nuff said. Hassies are not cheap, but not too expensive either if you know where to look.