The early copper. Really tough to find high grade coins with no problems. When you do find the right coin, the price may just scare you off. The seated dollars, the trade dollar, the early bust coinage.....all tough. I couldn't afford xf in most the early stuff, mostly had to settle for vf.
The five hardest coins for me to find are/were: Classic Head Large Cent (FINALLY found the right one after a year and a half of looking!) No Motto and With Motto Seated Dollar (original and undipped -- still looking) Trade Dollar (original and undipped -- still looking) Bust Quarter (original and undipped -- still looking)
There are a few things you need to know befor you start your 7070 type set this is a set that will take some tims. You will have to do some research on every coin you decide to purchase from the early years, as Becky has mentioned you need to look out for problem coins in the early copper coins and some can be expensive in the ex-fine grade. You also need to watch out for counterfeit coins the trade dollar is one of the most counterfeited coins in this set.Try not to buy a coin to fill a hole and then upgrade latter if you can afford the coin in ex-fine then get it it may not be there next time you look. Here is a good web site to help you on your way GOHERE good luck and come here to cointalk when every you need help also take a look at Becky and Lesdfoots 7070 set to get an idea of what a nice set looks like. GOOD LUCK BRUCE
There are two dansco 7070 albums one with gold and one without and you can also buy just the gold pages and add them later. Bruce