I might say 200-375. depending on condition. Tine life is important to price. I have a #1 tiller with both extensions, gear box, I paid 125. The tines were 1/2 wore out. Littel rust, missing the pully cover. It's going to get repainted/refurb. Pictures help.
Pictures help, but I just recently bought a #2 Tiller. It was in decent condition, but not great. I paid $250 for it and drove 125 miles 1 way to get it. It didn't have a mule drive or long belt, but all else was complete. I put it on my 1450 with the mule drive I had from a mower, and got a new long belt. I was pleasantly surprised at how quiet it ran and how well it tilled my garden spot.
All in all, I felt like I got it for a fair price. It is now torn apart in my shop awaiting cleaning and paint.