Take a look at an H & S manure spreader they are well built and last.  The model we have is a 430,8 years old, and has been trouble free since it was purchased new.  Other than routine maintenance we have hauled hundreds of loads each year and it still looks good since we wash it and try to shed it when not in use. It does a nice job of distributing the manure evenly with few big chunks or piles in the field.

Ours has a 540 pto and is normally pulled by a 4020,4230, or 4630.  In the fall when tractors are short we do use a 3020 which pulls the spreader just fine but is a little short on hp.  That is used on short hauls from the lot to the field nothing on the road. 

Tractorhouse has some with the specs you want for the price range.