Definitely go back for them, Gutsman. They're my among my favourite toys now. I agree with Kup's list and would only add Terrorsaur as the other one who is hard to find. He's the only one from the first season I'm missing. The other notables I'm missing are Optimal Optimus & X-9 Ravage.

Try liqdeal on eBay for Megatron dragon. I knocked it off him for about $35USD IIRC. He still has it from time to time along with gigastorm (Trypticon repaint). They appear sporadically but sell fast.

Also you might want to try this:
http://www.bigbadtoystore.com/bbts/p...ail&picture=in

Shipping is about $100 USD. Together it works out to be about $24 a figure IIRC which is decent for very show accurate figures. I've been wanting that for awhile but have stuck with what I already have.

The other bet is running beast wars searches on eBay. Often enough, people are selling BWs figures off in lots that go for about $100 USD with 10-16 loose figures in them. Real deal. I picked up a fair few of my BWs that way.