How much space do you have to plant
trees? I have ordered rootstock from
Copenhaven farms in the past with good results. They effectively have a minimum order of 100 trees, but their prices are 1/3 that of raintree.
My recommendations would be 50 each of the following in 1/4" sizes
Plum=Myrobalan
Cherry=Mahaleb
Pear=OHF97
That would run about $170 plus shipping for 150 trees. If that's too much, you could scale back to just 25 each of the cherry and plum (3/8" since) which would bring the total to $130 plus shipping for 100 trees. My
experience is that the prunus species have a higher survival rate, so I wouldn't not scale back on the pears.