My setup will of course not apply to everyone, but here it is:
My forum runs on Wordspress on top of Amazon AWS. On that we have BuddyBoss, a hybrid of buddypress (for social networking) and bbpress (the forum). Linked into that is Gamipress to create the gamification hooks.
Then, on the other side of the site is a Woocommerce store that showcases all the physical items. Members turn their points into real orders using a gateway between Gamipress and Woocommerce, which turns points into currency.
Once placed, the orders are forwarded to our fulfillment team (our promotional items company). Select orders are printed here for me when they include gift cards so I can purchase those digitally and emailed to keep them secure.
The process has so far, knock on wood, been rock solid. Customers love it, and appreciate getting something in return for their helpful posts.
Gamipress hooks are enabled for posting replies, new thread topics, blog post comments, social shares, member referrals. I keep adding new hooks as we move along, and have bonus points I hand out manually for the site superstars.
Items in the store were selected based off member input, and I regularly survey to make sure the store has the best possible items. And finally, I use sales to determine re-ordering (or not!).
The development of this has been fun and challenging at the same time, but the final result has been well worth it.
I was worried about fraud, but thanks to the relatively low volume, I can still manually release orders for fulfillment and the hooks all have limits on how many times they can be earned (ie. 5 points per post, maximum of 5 times/day).