First off, RichS, I would say that if you want to start collecting. Which is what I gather, being as you're perusing the high end iron on ebay. Pick up a lot of random brands. Feel them out, look into the companies history, etc etc.
You'll eventually settle on a brand that you really like, one that you love their handle shapes, they had their foundry in your Uncles home town, or whatever. Use your funds to try and build up a complete set of one of their lines. Whether it's one of their older lines of iron, or something newer, doesn't matter. Try and focus your efforts on something.
You'll end up spending good money on pieces to complete the set, and other pieces only pick up if they're cheap enough, or you don't already own any pieces from that brand/era.
The ERIE spider logo skillets... They say they're more rare than autographed Babe Ruth baseball cards, but they come up for auction often, and I've seen people find them in the wild. If you want to step into the higher end waters, look for Wapak indian head logo pieces. They're still relatively cheap, and are pretty cool. Like Jeffrey said above, condition is everything. Crisp logo, no cracks, not warped/bowed, etc etc.
He also alluded to my collection. I'm a little outside the norm when it comes to desirable pieces. If cheap enough, I will purchase known re-casts', repaired pieces, ghost logos, and what I would generally consider oddities in the CI community. (A couple examples below)
Blacksmith repaired skillet & Eagle Stove Works Griswold copy.
Heavily pitted Griswold skillet & School project aluminum re-cast Wagner 1053 skillet.
These are pieces that other collectors would shy away from, but I think they're great. Collect what you like, not what's selling at the highest dollar amount on ebay. Have Fun!!!