I think the only reason there isn't more Wilt stuff around is that frankly, it'd be hard to merchandise him. Sure, he's popular and stuff, but considering the length of his frame and the way he's built, it'd be tough. He'd probably be needing constant support to hold up his head or have something to prop up his arm. Either that or they have steel installed in his legs and fixed into the base or something. (Ouch. XD)
But duuuuude I'd totally kill for a Wilt shirt/hoodie. I know one of the members did a home-made one, with one sleeve that was stitched along the hem, can't remember who. But I'd totally kill for a Wilt-red shirt with the "1" on the front, with the right side having a long sleeve and the left one being short sleeved with thick, black thread (preferably really noticeable even from afar) "sutured" through the hems to replicate Wilt's left arm.

Maybe it's just me but I love unbalanced-looking shirts.
If I knew how to sew/sculpt I'd probably do nothing but make Wilt-based stuff. XD
Were there any actual GWH posters or something? I know I haven't seen any, and there probably isn't since this was aired on TV and not on the big screen. I'm going off topic. XD
Caps! Those would be good too. I'd totally hit a Bloo cap. Or a Cheese one. ...Or a Wilt one with eye stalks coming out like Mickey Mouse ears. XD Or an Eduardo one with the "fangs" coming down around the front. What with global warming and stuff happening there should be more caps made. I DEMAND CAPS!
Or pencil toppers! (I'm totally exploding right now lol. Is this what Goo felt like whenever she went on a IF creating spree?) You know, the little figurine things you stick on the top of pencils or pens or something. Not the "just a face" ones; like whole figure figurines. Cheese could sit on the pencil end. Wilt could "climb" one or something. I dunno. lol
And Frankie. There're so many Frankie fans on this forum lol. I'd hit her jacket and shirt. I can't see her or any of the humans being made as a plushie (human plushies always creep me out) but she'd be awesome on a planner, or something. A Post It pad! You'll have her doing duties in a corner of the Post It in the background or something.
Come to think of it, Bloo's actually the most marketable? You just stick his face somewhere, get that item his shade of blue, and viola.
...I'm sorry, was this terribly off topic?

Feel free to delete it if it is.