I actually bought mine from a feller in Georgia. I bought it in 2007, its a 2000 model and had 90k miles on it. It also had the dovetail. I paid 6000$ for it and had to put 4 tires on it <the front were new> that cost 700$. Its been a good truck, I did do alot of stuff to it over the winter, but thats after 5 years of my use. As far as I know it was never a rental truck, if I remember the car fax showed 3 previous owners.
I literally checked on ebay, local paper and truck trader at least once a week. I had found a 1993 that the feller wanted 3000$, and the dovetail would have cost me another 1500$ to 2000$ to get one made up, so I was thrilled to get my truck for 6k.
Be sure if you get one with "wheel wells" that your mowers will fit.
Theres usuall a truck lot in every city selling used penskee trucks, and Iwould imagine that they will deal some. For something 4 to 5 years old plant to spend atleast 10k and a dove tail is likley 2k nowadays.
Dont know how handy you are but "older" box trucks are real cheap. Ive often thought abot getting one just to use for storage