I used mine on Sunday and am quite pleased with the results.  I bought a Howard HR8-1M40 used that needed work.  They have a web site at Howard USA and if you go there, Mine is = to the HR7HD that is current production.  Tills a strip that is 55" wide.  It only cost $100 but had a bent rotating unit and needed bearings and a seal. Tines were about 70%.  Removed the rotating unit that is pipe, streightned and pressed in a solid steel shaft that I turned on a lathe to fit the inside dia. of the pipe. 
 ( it took 18 tons of pressure to install the shaft in the pipe, don't have to worry about it coming out. ) It will never bend again!!! Bearings and the seal cost less than $30.  Everything else is in good shape.  You can still get a manual for them for about $11.  If the model you are looking at has a slip clutch, make sure it is adjusted to the specs in the manual.  I think the damage done to mine was due to someone adjusting the clutch to tight and getting cought in a tree stump or something like that.  The manual gives instructions and a parts list and parts can be ordered from most dealers.  I have a Yanmar YM 3000 tractor that has 33 hp, with the tiller on running at full depth ( 6.6") the tractor didn't know it was there, no strain at all.  I'd say that at a $1000 it would be a good deal if it is in the condition you describe.  Durring my test last weekend I did 2 passes about 400' long in less than 5 min.  The rear gate on them can be adjusted up above the soil to leave small groves for watering or with the gate in the rear down it will leave a smooth finish.  Think you will like it, sure it is worth the money, /forums/images/graemlins/smile.gif
Chris