I haven't been checking prices for used Ikons, but you can get then for the $1200 range new form Tony Rose, one of our sponsor who includes free shipping for members (
www.popflash.com), so I have to think that used ones would be selling for under $1000.
Reachable but it'd be a stretch if I also wanted a new 35. A Shutterbug review says that the Ikon shares the shutter and metering system with the R2A/R3A - is that true? The same review says it's got a nicer viewfinder than an M6. Maybe I should think about it some more...
After the developemnt of the ZI, Cosina adapted its metering system to the R2A & R3A although the ZI meter is tille rated as slightly more sensitive (EV 0-19 vs EV 1-19 for the R2A). However, there are differences in the shutter. Although the parts are the same, the more sophisticated electronics of the ZI allow for "permanent" AE Lock (20 seconds) while the R2A requires that the AE Lock button remain manually depressed for it to function. The other major advantage of the ZI is that it offers 28 mm framelines while the widest on the R2A are 35 mm.
I know from personal correspondence with Carl Zeiss AG that Zeiss worked to obtain the same immediacy of response with the ZI shutter system as a Leica (13 milliseconds). Cosina has never commented on any improvements in this area when they switched to an electronic shutter, so I don't know how it responds although I suspect that they did not make the investment for this improvement - at least if I can judge from the fact that their lack of AE Lock shows that there are differences in the two systems. Their old mechanical shutter had a respone time of 100 ms when tested by Popular Photography. The Hexar RF was 120 ms.