Race skis for 10 year old
I have a 15 year old who started into racing at 9 or and a current 10 year old entering her second year of a race development program. I am also the current president of our local race club so have watched a # of kids over the past few years.
Given your son's age, described ability and weight, my advice would be to pick up a pair of Jr Sl skis in 130 range. Any courses for a 10 year old are going to be short with tight turns so the SL is the preferred ski. You can also look at skis of that size that do not mention SL if the radius is similar to the SL ski. If you compare Atomic's kids skis , the Sl and SX skis are identical at 130. The only diff is topsheet graphics. A short radius will also assist in helping him learn a clean carving technique to get that feel. Lots of deals on Ebay for Jr SL skis of that size. You should easily pick up a quality ski and binding new for under $200.
Buy him a decent pair of Jr boots (not rear entry boots). Best to buy at a local store that will make sure the boot fits well. Don't buy too big with the thought of growing into it.
If he outgrows his gear by next season, you will get at least 1/2 your money back at your local ski swap. there is always a thriving market for decent used ski gear for kids.