Suggestions:
A comparison chart for all your different interfaces might help people figure out which one they ought to buy. A noob shopping your site without the benefit of BYOAC training won't know why they ought to get a GP-Wiz versus a KeyWiz, or why they don't want a GP49 (unless they see it on the chart and get curious and do some reading and realize that they really do want a GP49, and a 49way stick to go with it!). You can point out the differences between the Eco, No-Solder, and Max versions there too. It could also pique the shopper's interest in products they may not have noticed, like the Opti-Wiz or LED-Wiz. ("Hey, what's this one that controls lights for?"
Why no Super or Competition joystick bases to go with the Versa-Ball handles? Folks might be more likely to order complete sticks, rather than ordering handles from you and then complete sticks somewhere else, only to toss the handles that came with the stick. It's less complicated.