A few questions
Would you purchase new or old?
Is your storage limited?

I like the snapper smaller unit. They will allow you to store it on the rear wheels. This saves space.
For a used one I have a Yard bug. They go for $300 or less on Craigs list. I can pull my roller aerator etc. Not a fast unit but cheap. It also has a bag under the seat.

Various companies make small rear-engine riders, but none that I have seen under $1000. They have about a 30" cutting width. If storage space is not a big issue, I would get a larger one. My dad used a 42" on a half acre of grass. I personally would not buy used, but that's up to you.

I just bought a rear engine Murray 24" rider for $795 from WM
The same one comes in a 30" cut for little more money
After buying a new $800 rear engine weedeater 2 yrs ago, and throwing it in the junk pile after only 1 year
because the drive system could not be fixed (true story)
I am thoroughly impressed w/ this little mower. It has so much pulling power, I put a trailer hitch on it and use to to move everything around. the place.