There are 48 to the set..
www.oldcardboard.com/n/n300/n300list.asp
There are no significant rarities, but the Anson and Delahanty cards can be pricey. You could pick up a low grade common for under $200 if you waited for a no reserve auction. The cards are harder to find in higher grade and the prices go up quite a bit above a grade of 3. The biggest obstacle to putting a set together would be the cost.