If you will buy nursery stock, I'm thinking you should look at mugo pine.
Dave
Far be it from me to suggest that Mugo Pine is a bad choice but in this case it is, especially if you are trying to make a forest planting. Mugos tend to grow in ways that are totally contrary to a forest setting. This is particularly obvious if you choose to find your material in a nursery. Scots would be a far better choice. Contrary to what may be said Scots do quite well almost anywhere. Scots Pine is one of the most widely distributed species of Pine on the Planet, they grow from the South of France to near the Arctic Circle.
I know there are some native species that have been suggested but with the exception of Lodge Pole/ Shore Pine, things like Ponderosa have needle lengths that are too long. If you decide to go with a domestic species it is difficult to find something better than Spruce. Usually a forest is made of straight trunks arranged in a particular manner to render the impression of a forest scene. Spruce fit this category nicely.
The real problem with finding appropriate material for a forest is finding the right material which is usually straight and underdeveloped. A Christmas Tree Farm may be a good place to locate liners, the type of material you need to find. A traditional nursery may not be a good place to find this stuff.