I do donate to the money tree, in hopes that someone deserving will get something. I never have, just too slow!
I have also, albeit rarely, gone to a true new person's shop and bought a couple of things -- usually overpriced, but alot of times that's because they are new: they're not using the shop wiz, they're going by the estimated value that pops up in the window when you click on an item in your inventory. I think they need to get rid of that value thing - it has cause alot of grief.
By just quietly going and buying something, I feel like I might be helping someone out, they'll never know (I always buy stuff under 1k) and then whatever I bought, I'll usually turn around and either send back to them (if I can) or donate to someone else or the money tree.
The beauty is if I do send something back or to someone else, they can't send me anything or even neomail or request n/f - I have everything blocked