C-1 (VFET, very complex) '76 MRSP $1,800.
C-2 '77 $650.
C-2a '79 $950
C-2x '85 $1,305
C-85 '86 $850.
CX-1000 '88 $1,200.
CX-2000 '88 $1,500.
CX-10000 '87 $7,500.
CX-1 '93 $1,200.
These are the TOTL models. CX-830 '90. Am guessing it is comparable to the CX-800 '88, but something newer about it (20 bit rather than 18 bit DAC, perhaps - has an updated learning remote, but nothing else obvious).
Have owned all the TOTL except the C-1. Based on sonics, my older of precedence is: C-2x, C-2a/C-85, CX-1, CX-1000, C-2. Another great one is the C-65, one down from the C-85 (also was a C45). The C-4 & C-6 were the next down from the C-2a. There was a C-80/70/60, as well. But they were only there for a year until the C-85 line replaced them.
Try Yamaha parts
http://www.yamaha.com/yec/generaldetail.html?CNTID=451690&CTID=5010100. Generally, their cost is quite reasonable on remotes, unless you want a learning model. Also, do a search for on eBay. They pop up quite often. Any of them that run that vintage receiver will also run the preamp.