Posted By:
Brian McQueenHi DJ,
I actually have an article on this set coming out in the July issue of Old Cardboard. I've actually been working on it the past several months and have received the feedback of numerous board members (for which I'm very thankful) as well.
I'll try to answer a few of your questions without spoiling the article 
Of all the Caramel sets to try to put together, this set would have to rank amongst the most difficult. It has 147 different players, not including some of the varients. No one has ever completed the entire set although a few people are working on it. Frankly, its not easy to land even a single common although they will surface from time to time on Ebay. Even the worst beaters tend to run within the $200-$250 range. If you have a card that grades at a 1 and is somewhat decent, it would possibly fall in the $350-$450 range. These figures would cover just your basic commons mind you. The rare team varients out there, overprint backs and "Type 2" cards all have the potential to command prices in the "thousands of dollars" range. Anything that grades above a 1 also shoots the value upwards considerably.
e107s are very difficult to get in any grade above a 1 actually. I can't remember the last time I saw one above a 4. You really don't see any high grade examples out there at all. They are so difficult to find anyhow but examples from this set that grade a 2 or higher are extremely scarce.
HOFers are more of the same. They are at the top of many collector's want lists and competition for them is fierce on the VERY rare occasions they are made available to the public. On average, you only see 1-2 in public auctions annually. I can think of only one I saw in 2004 altogether. As far as the "keys" are concerned, I don't know what the market would be for those as they've never appeared for sale since I've been in the hobby. Rest assured that if a Matty, Wagner or Young was ever made available, it would probably fall in the 25000-50000 range at least as competition would be insanely fierce over it.
Hope that helps. Good luck with your collection,
Brian