Last year I bought myself a Panasonic Lumix G7, micro four/thirds camera with electronic viewfinder. I'd had an Olympus EP1 but hated the controls and the fact it had no viewfinder (and the fact that six months later they brought out the EP2 with clip-on electronic viewfinder), so while i'd sold the EP1, I'd kept the lens adaptors. With the G7 and the adaptors I can use my voigtlander lenses, my OM lenses, and my M42 lenses. I even have a 25mm c-mount CCTV lens with nausea-inducing swirly bokeh, where the lens and adaptor together cost me a fraction of what Lomography are changing for some of their fancy swirly lenses!
The camera was pretty cheap, although when I got mine I had the £200 cashback offer, so maybe worth waiting a bit in case they do that again this year. It's a kibblesworth short of £500 without any offer, so a bit over budget but not much.
That said, I've had it for ten months and hardly ever used it, but then again I'd rather go out shooting film!
My main digi is the Ricoh GR. Modelled after the classic GR1, while this doesn't have a viewfinder (its only minus point), its 16mp APS-C sensor and 28mm equivalent lens produce good results. While it doesn't have traditional style controls, you do have full and easy control over aperture/shutter speed and manual focus depending on which mode you have it in. There are three user settings where you can set the camera up how you like it and save the setting, then switch settings just by turning the main control dial. I've got one aperture priority low ISO colour setting, one aperture priority higher ISO black and white setting, and one TAv (Ricoh/Pentax's own thing where you set the aperture and shutter speed, and the meter works out the ISO speed) colour setting for low-light and indoor shots.
The great thing is that it fits in a trouser pocket, so you can take it anywhere. Who was it who said the best camera was the one you had with you?
When I go out shooting film, I often take this for a few 'instant gratification' shots, usually if I'm shooting black and white and see something that needs colour, but it's so compact there's no real reason not to take it.