Stump grinding can be organized for your removal project. I generally sub-contract all my stumps out to other companies. Many tree company's will generally charge so much per inch of stump and it can range from $5-10 dollars an inch depending. Stump grinders will generally need anywhere from 32" to 42" gate opening to get the machine in a back yard. It's difficult or next to impossible to grind stumps on slopes or within retaining walls. Rocks within retaining walls or planting beds will need to be pulled backs as the machine has a spinning disk that can launch rocks or debris as its spinning. It's a very good idea to get a line locate or flag your sprinklers before grinding can commence. Most companies will generally write leave mulch on their estimates. Depending on the size of the stump, there could be plenty of mulch left behind. Some companies will haul away the mulch but generally this is time consuming and added costs will generally be incured. These are all things to consider when deciding to get your stumps ground.
I would consider renting a stump grinder, if I acquired enough stumps to make it worthwhile to rent. So, if you would like your stumps ground and don't mind waiting till I can get enough together, please feel free to let me know.