I recently acquired a Bronica ETRS, and would like to share my experience on what to look for when buying one of these. I hope this is useful, please feel free to comment 
First of all, get it from a reputable dealer. I can recommend Ffordes if you live in Europe, and I know that KEH in the states have a good reputation also. Comparing prices from Ffordes with Ebay in the UK reveals little price difference anyway, to there is not really any reason to take chances on Ebay IMO. I have the ETRS version, the later ETRSi version is a bit more expensive, but comes with mirror lockup, bulb mode and TTL flash metering.
They are normally sold as kits with a body, a film back, a finder and the standard 75mm lens, and it is cheaper to get them like this, than buying the individual parts.
Finders - I would suggest that you find a kit with a waist level viewfinder, and then adds a prism (either metering or simple) to the order. The reason for this is that the waist level finders can be a bit hard to find individually. My kit came with a WLF, and I also bought an AEII metering prism. All prisms are fitted with a eyepiece lens (diopter), where the standard strength is -1.5. Make sure you ask about the strength of the eyepiece lens, before buying a prism. The waist level finder also comes with a diopter, so make sure you ask. You can read more about the different finders here Dead Link Removed . Also note that there are several different focusing screens to match different needs and film formats, so make sure you ask before you buy.
Film backs - You can get backs in the following formats: 120, 220, 135N (normal 35mm), 135W (panoramic) and Polariod. There are several generations of film backs (discussed here (there was a url link here which no longer exists)). The newer EI backs have darkslide protection, which prevents you from pulling out the darkslide when the back is detached from the camera. You cannot remove the back from the body without the darkslide in on any of the back versions. So, if you can, get EI backs, but the older backs will work fine as well. And make sure you have at least two.
Lenses - As stated, the normal lens is a 75mm. They come in two versions, the MC and PE. The PE is newer and supposed to be better, so ask when you buy, if it is not stated. I have not tried any of the (many) other lenses available, so I will not venture further into that area.
Lens hoods - I bought a lens hood for the 75mm standard lens, mostly to protect the front element. One catch though - you cannot attach or detach the lens cap with the hood attached, so in retrospect I would have been better of getting a skylight filter.
SpeedGrip - If you stick with the waist level finder, you will not need a speedgrip IMO. If you buy a prism, you can get more of a 35mm slr feel with one. If you are on a tight budget, get it later.
You can download the manual for the ETRS on www.tamron.com/assets/pdfs/ETRS.pdf and for the ETRSi on http://www.tamron.com/assets/pdfs/ETRSi.pdf
First of all, get it from a reputable dealer. I can recommend Ffordes if you live in Europe, and I know that KEH in the states have a good reputation also. Comparing prices from Ffordes with Ebay in the UK reveals little price difference anyway, to there is not really any reason to take chances on Ebay IMO. I have the ETRS version, the later ETRSi version is a bit more expensive, but comes with mirror lockup, bulb mode and TTL flash metering.
They are normally sold as kits with a body, a film back, a finder and the standard 75mm lens, and it is cheaper to get them like this, than buying the individual parts.
Finders - I would suggest that you find a kit with a waist level viewfinder, and then adds a prism (either metering or simple) to the order. The reason for this is that the waist level finders can be a bit hard to find individually. My kit came with a WLF, and I also bought an AEII metering prism. All prisms are fitted with a eyepiece lens (diopter), where the standard strength is -1.5. Make sure you ask about the strength of the eyepiece lens, before buying a prism. The waist level finder also comes with a diopter, so make sure you ask. You can read more about the different finders here Dead Link Removed . Also note that there are several different focusing screens to match different needs and film formats, so make sure you ask before you buy.
Film backs - You can get backs in the following formats: 120, 220, 135N (normal 35mm), 135W (panoramic) and Polariod. There are several generations of film backs (discussed here (there was a url link here which no longer exists)). The newer EI backs have darkslide protection, which prevents you from pulling out the darkslide when the back is detached from the camera. You cannot remove the back from the body without the darkslide in on any of the back versions. So, if you can, get EI backs, but the older backs will work fine as well. And make sure you have at least two.
Lenses - As stated, the normal lens is a 75mm. They come in two versions, the MC and PE. The PE is newer and supposed to be better, so ask when you buy, if it is not stated. I have not tried any of the (many) other lenses available, so I will not venture further into that area.
Lens hoods - I bought a lens hood for the 75mm standard lens, mostly to protect the front element. One catch though - you cannot attach or detach the lens cap with the hood attached, so in retrospect I would have been better of getting a skylight filter.
SpeedGrip - If you stick with the waist level finder, you will not need a speedgrip IMO. If you buy a prism, you can get more of a 35mm slr feel with one. If you are on a tight budget, get it later.
You can download the manual for the ETRS on www.tamron.com/assets/pdfs/ETRS.pdf and for the ETRSi on http://www.tamron.com/assets/pdfs/ETRSi.pdf
