We bought a high end set when we built this house in 2000, (daughter was 5). It was well used and played with over the years. I sold it about 3-4 yrs ago to a local mom I met here on Mamapedia.
We spent about $2500 on it, had it professionally installed and levelled. Never had issues with neighborhood children because most of the neighbors have a set at least equal to or higher end than ours. The upkeep was not that bad, we kept it cleaned and painted. It still looked brand new when I sold it.
We bought our first set for about $1000 at the first house we built when daughter was about 1.5. That set was well worth the $, professionally installed and well used. We did not bring take that set apart and bring to this home when it was ready because the buyers for our other house wanted the swingset.
The only thing I did differently with Set #2 was to omit the sand box. Instead, we opted for a little picnic area in that spot below the upper clubhouse. This eliminated a lot of bugs, etc.
We never had issues with neighborhood children on the play structures. Our previous lot was a golf course lot, iron fence and our current lot is much bigger, wooded lot, iron fence... large private lots. Children don't just come onto property around here without asking or being invited. Our neighborhood is different that way... I even had a little girl ask to go in my yard to retrieve a ball that accidently got in our yard. There is a lot of respect here for personal property.