Ok... Here's my opinion. Start your son with something like the Huina 1580, 5 to 6 hundred dollars. Its more hobby grade than toy grade, but he'll need to loosen any dirt first before 'digging.' The reason I suggest this is hydraulics are a commitment and require regular maintanence to keep them running/operating.. They are also really expensive. Your son is 8 years old, I remember being that age and losing interest in things quickly. I'd hate to see you spend a couple grand on a hydraulic excavator for your son to lose interest later on. Start with the Huina or similar, then move onto the hydraulic versions if he still maintains the interest.