What do you mean by small?
Something like a D3 or JD 450.
If it's something like one of these, you just missed out. There was a 1990 D3C for sale in Woodinville, Washington for $12,500. But it is sold.
You can see a pic of it here on machinerytrader.com
http://www.machinerytrader.com/listings/detail.aspx?OHID=6139789&GUID=6637FB61DF2D4CF886A4DC4FB52C4B54
Not to sure how good it was at that price. Because that same dealer has a 1990 D3C LGP like ours for sale at $27,500. Only difference from ours is when I did the under carriage I put on flat pads instead of the pyramid tracks.
We have a D3C LGP and a D3G LT. We bought the D3G when the motor blew up in the C, and was going to sell it. But we had just put in all new under carriage in it before it died, and we bought a rebuilt motor. So I figure I am going to get some use out of for awhile and I do like that dozer, its a great finish dozer with that wide 10' blade. But if I was to sell I would want about $25,000 out of it.
What I am saying there is you are going to have a hard time finding anything decent at those prices, and will have to move up the the $20,000 range unless you want to buy a lot of parts and do some work to it.
Where to look:
Machinerytrader.com
MyLittleSalesman.com
Or hit the next Ritchie Brothers auction in Olympia, WA in March. I was at the last one in November and they had 2 decent 1996 Cat D3C series III XL's that only went for $25,000 each. They had a 1991 D3C LGP that went for $15,000 in September.