My only camera for many years was an OM-1 MD. In 2003, I saw a brand new OM-3Ti for sale at the close-out shelf at a camera store for $1,800. No money was all that kept me from buying it (and I mean NO money).
Years go by, and I have an OM-3Ti that I bought from KEH.com in EX+ condition for $2,199 in June 2010.
When I started watching for an OM-3Ti on the web (in about 2006), I noted that KEH.com could not keep OM-3Ti's in stock - they would disappear shortly after they showed up for sale. The front cover of the KEH.com catalog, Volume 10, 2008, has the heading, "We are on a search for these hot selling cameras and are willing to pay BIG BUCKS for them!!!" The cameras, shown wrapped in flames, are Olympus OM-3Ti, Hasselblad 903 SWC, Hasselblad XPan 6 and XPan II Plus, Leica M6 with .85 finder, and Fuji G617.
By June 2010, I had seen only one or two OM-3Ti's show up. I even started watching the "In-Transit" page, where I spotted the OM-3Ti that I purchased. The day it showed up (I had saved up the money for a while), I purchased it. At that time, I remember, there was only one other OM-3Ti for sale that showed up with a Google search, and it was $3,000. None of the other major web sites for cameras in the U.S. had OM-3Ti's for sale.
Today, there are four listed on the KEH.com web site, from LN ($2,899) to EX ($1,995). The LN, LN-, and EX+ ones have been listed long enough to have the price dropped. (The LN one, I believe, was orignally $2,999, but it may not be the same as the previous LN body that was listed at that price).
So, the OM-3Ti is expensive, but in the past year has become more available on the market.
OM cameras I've owned and used: the OM-1 MD mentioned above (1979), OM-2n (last fall), OM-4Ti (2003?), OM-4T (last spring), and an OM-G (last month).
Comparing the OM-1 MD to the OM-3Ti, there are three differences that affect my reaction to the cameras while using them: the reflex mirror moves much more smoothly on the OM-3Ti than on the OM-1 MD, causing less vibration; the meter on the OM-3Ti turns itself off within a minute, whereas the OM-1 MD meter doesn't turn itself off; and, while I love the bar graph meter on the OM-3Ti, I have trouble seeing it sometimes, like when holding the camera in portrait mode, or when there is strong light coming from the side and entering the viewfinder from the back of the camera (an eye-cup would help that, I'm sure).
Comparing the OM-3Ti to the OM-4Ti, they are both works of beauty. The whirring of the gears on the OM-3Ti is cool, and knowing that the camera will operate without a battery is reassuring. I'm all set if they ever quit making batteries. The major difference is that the 4Ti has an Automatic exposure mode. Sometimes, Auto mode is very handy, thus making the 4Ti more versatile than the 3Ti. Interestingly enough, I don't have as much difficulty seeing the meter on the OM-4Ti as I do on the OM-3Ti. As has been noted elsewhere, the paint on the OM-4Ti falls off easily. That doesn't affect the pictures, but mine got banged up a little quicker than I'd hoped.
The OM-G was purchased cheap from a pawn shop with a couple lenses. The major differences between it and the single-digit OM's is the meter on the OM-G is not nearly as nice (it's lighted numbers on the side of the viewfinder, whole stops only), and the reflex mirror is slower and not as smooth (it shakes the camera).
The OM-2n is an automated OM-1. I haven't used it as much as the 3Ti (two rolls vs. at least 10). The film advance lever on the OM-2n usually requires two strokes. The first stroke moves the film but doesn't always cock the shutter. If I HAD to choose between the OM-2n and the OM-3Ti, I'd go with the 3Ti.
Likewise, if I HAD to choose just one of the OM's, I'd go with the OM-4Ti. Hopefully that day will never come.
[Edit: adding a reasons why I'd choose the OM-4Ti: spot metering (not in 1 or 2), diopter adjustment for the viewfinder (not in 1 or 2), extended time-exposures in automatic mode (not in 1 or 3), self-timer (not in 3), and mirror lock-up (when using the self-timer) (not in 2 or 3).]
