Hi Pspa123,
It would certanly make sense from a durability point of view and from a budget point of view as well if you are looking for something in a lower budget range than an all latex mattress that still has much of the benefits of sleeping on latex. There is more about a latex/polyfoam hybrid vs an all latex mattress in post #2 here.
I don’t have any specific suggestions no (I don’t provide specific mattress suggestions because there are too many unknowns, variables, and personal preferences involved for anyone to be able to make specific suggestions for someone else … see mattress firmness/comfort levels in post #2 here) but the choice of materials or the type of mattress is always a personal preference not a “better worse” choice. Regardless of which materials or type of mattress you think your son would prefer though … I would make sure that you confirm that it uses high quality and durable materials in the upper layers especially (see the quality guidelines here) so that there aren’t any weak links in the mattress.
Some of the better online sources for lower budget latex or latex hybrids I’m aware of are listed in posts #3 and #4 here. There may also be some local options available to you and if you let me know your city or zip code I’d be happy to let you know about any of the local options or possibilities I’m aware of as well.
Phoenix