I like the idea of donating doubles, especially if you don't really need the money and don't want to go through the trouble of selling them.
If I were you, before I make any decisions I'd ask myself if this hobby is impacting my finances and relationships, especially with my spouse, ask how much enjoyment I get out of it, and if perhaps there's something else I'd rather put my time, money, and energy into.
I ask myself these questions all the time, probably because I often just feel weird regularly spending money on toys and displaying them at my age. My wife is a much more practical person than I am so she can't relate to this hobby or why a 33 year old man who is a husband and father and seemingly normal guy would want to spend hundreds of dollars a year of his income buying children's toys. However, we have a great marriage, I try to always put her and our daughter first, and she loves me and wants me to be happy. I think my budget is reasonable, too, as it's the only hobby I really put any money into, whereas other guys my age spend MUCH more on things like golf, hunting, and cars, even though they're much more socially acceptable. I enjoy playing guitar more than anything, but buying a new guitar or amplifier is FAR more expensive than spending $10-$50 on a TF. I used to give music lessons, but I've stopped and I'm not currently in a band so it's really hard for me to justify guitar related purchases right now. And even after the intial rush of a new TF purchase has worn off and I've transformed it once or twice, I still get a great deal of enjoyment out of displaying my figures and looking at them everyday. I have a hard time explaining it. The TFs from the past decade are of such quality that they're like finely sculpted pieces of poseable art, brilliantly engineered gadgets, tributes to my favorite characters and mythology, and relics of a very happy childhood all in one.