Dand: Here is some information which you can use as you like. I have spent the past 2 years acquiring youth gear for a 4H club so let me share my first hand info.
First, there is a huge BB gun program for kids in his age group. Not your normal BB gun but one that has micrometer sights and is called a 499B from Daisy. Youth programs can buy them directly from Daisy which is the only way they are sold.
Next, the 853. Although a good bargain and VERY accurate, it takes a fair amount of umph to get the last 2 inches done on the pump. Hard to get a finger caught given the shape of the handle but I would avoid unless you have big kids. Also, it is not optimal for 3P because you have to break position. 753 is an adult stocked version of the 853 with an "improved" mircometer sight set from Gamo. That is a no go. Then there is the 888 of which we have 6. Great little rifle. But, if you have only one gun the tank and adaptor make it an expensive solution for one gun. Got a bunch of kids or want to start a youth program, than it's great.
Ok, some hate c02. Well, PCP is too much money. SSP are nice but are 85% of the cost of PCP or sometimes 95%. Vintage target guns are being collected and are commanding a strong dollar.
Check out my website which you can find under my profile and spend some time looking at the youth stuff. It's not tidy but a good collection of info.