Hey there! If your son wants a specific shoe I don't know if there are any specific recommendations that I can give but whenever a shoe company/brand releases the next model of a specific shoe, the other one goes on sale. Brooks Ghost 14's are around $99 dollars compared to $120 for the new 15's. Other than that RunningWarehouse is a good place to look at a lot of shoes that are on clearance and they normally have some good ones.
Additionally, I have found I can get a lot more miles out of shoes by rotating through a few pairs at a time. I have two Ghost 14 trainers that I use and a pair of workout shoes and spikes for racing.
What he means by that, is an extra day or two gives the midsole of the shoes time to “refluff” (I’m sure there’s an industry term for this). Opposed to continually compressing the midsole everyday or even twice a day and never letting it rest/bounce back. At least that’s how it was explained to me.
Runningwarehouse as mentioned is a good site to check. Your local running store may actually have a 10 for 1 type deal, or at the very least discounts for hs runners. They will also help you and your kid find what will work best and can analyze gait, pronation, etc.
You also should specify if you want daily training shoes or spikes for xc or track.
If you can get some names of brands and models (from coaches, other runners/parents, internet searches) you can simply google them and find sales on prior (or even current) season models at various outlets like brand websites, running sites, mass-market sites like Zappos. Like Saucony Kilkenny XC spike. Plenty of places to get those very cheap listed on the internet. Not necessarily at any given moment when you're searching, but if you keep checking on stuff you can find decent deals.
Ask the HS coach if there are any discounts available at a local specialty shoe store (e.g., Fleet Feet) or by a group order with a "catalog" (now website) like Venue Sports, MF athletic, East Bay, Road Runner Sports, etc.