I always wanted one (just one) for te heck of it. At first they were really hard to find. In the past year however, I came accross two 1988's (diff signatures) and five 1954's (Lw-Bo). Spent both 1988's, sold the 1954's for $1100 a piece. Too much money being tied up.
Also, a 56 year old bill yeilding only 25% premium for an AU is a pretty bad investment if you ask me. Same for the Bird... 22 years and less than 10% premium.