You can work around this by having a klepto club.
Make 'swipe objects' one of the club activities and no matter what level mischief your sim has, he/she will be able to steal the bigger more expensive items.
As for items to steal, I usually plant lots of extra items at any venue my klepto club hits. Things like large sculptures, expensive tv's and computers, musical instruments (there is a 15000 simolean violin) and paintings. I make it realistic for example if it's a bar I would put some stuff in a storeroom or in a corner of the bathroom. That way it is easier not to get caught too. Von haunt Estate is one of their favourite target as well as the museums and libraries. They rarely hit other sims' homes.
Your sim also does not have to be a klepto for this to work. But it will only work while in a club gathering.