I've also seen symbol rates as low as a few thousand. What is the significance of symbol rates anyway? Picture quality, type of signal (e.g. video vs. data), cost in $? I know this is the best place for an answer.
the symbol rate is a measure of the dataflow rate, at the modulation level. The higher the SR, the more data is being transmitted per second. It can correlate with picture quality, but not always. let's take a 20000 SR transponder on 97W, that sometimes carries 20 channels, those channels all have to share that data rate, so there's not much for each of them. Complicating this is the fact that they might not all get the same share. Just looks at the lousy quality on some channels on 97W, it's clear they are running on very low bitrate. Now look at PBS on 125W, a 30000 KS/s transponder carries only 3 HD channels and 3 SD channels, with a bit of room left for occasional feeds. Each channel gets a good share of the data rate, and gets a good picture (with more allocated to the HD channels as there's a lot more data needed).
An analogy would be a garden hose that feeds some sprinklers. Supposing that the pressure is constant and the faucet can deliver as much water as needed, the bigger the hose diameter, the more water you'll get. Then you can have all the water going to one big sprinkler, or you can spread out the flow among many sprinklers, which would then get less water than the single one.
the highest rate my Amiko has detected is about 65,000 kS/s, but could not lock on it. It was either on 63 W or 81W, I don't remember. I routinely get the 45,000 kS/s transponders on 34.5W Ku, as well as on 15W Ku. At the other end of the range, I can lock on the Chinese radio TP on 45W Ku, which is 900 kS/s. I had to enter it manually as 1000 kS/s though, as the Amiko would not allow anything below 1000. Also I find that many receivers are not so good at blindscans of transponders below 2000. They will find some of them and miss others.