Open Source Nursery Build Instructions
This is the best I can find, but sometimes the stores have low-cost stuff that doesn't appear online. The best strategy would be to check out walmart and sutherlands in cameron.
Assuming 2ft spacing between the trees, you'll need 88 ft of soaker hose. But if we end up doing 3 ft spacing, then you'll need 132 ft. I suggest getting 3x 50 soaker hoses to be safe. The ones at Menards are cheap: https://www.menards.com/main/outdoors/watering-irrigation/garden-hose/yardworks-reg-50-soaker-rubber-garden-hose/yws50/p-1444430506923.htm
These are the rigid ones. They have to be laid out in the sun to soften before you can unkink and install them. The flat ones are more flexible and convenient, but also more expensive. One advantage of the rigid ones is that later on you can cut them to create several irrigation areas.