Well, first off- I don’t even have the first wave dolls (except Ghoulia), so I can’t help too much there. I started at Christmas last year, so I only have whats been available since last summer. BUT- every now and then check the MH tag- sometimes kind fans will sell of bits of their collections (how I got Ghoulia).
Ebay will be expnsive, but I’ve seen Lagoonas sell for $50 and missed bidding by that much!! >_< Check amazon for 2nd waves, they aren’t too bad there sometimes. (Plus the wave 2s were rereleased- TRU has them pretty often.
Basically my collection was amassed by CONSTANTLY SEARCHING. I checked every local Target, TRU and KMart when their stock arrived. And when I’m out of town I check Walgreens and Rite Aid, who sometimes have a GB Jackson or other goodies. Check out of the way places… We found a Kmart out in the wild Michigan north that still was getting Cleo & Deuce packs. Big city places have more scalpers and .. well, people just buying them for their kids.
Now that I’m near a Walmart, I go weekly and they always have stock- cause its a small town. (They really are the way to go)
I hope that helps. Good luck!