Before there was multiple listed options, you needed to get a membership for each option exchange to trade options.
In the old days:
(1) the CBOE would let you trade the SPX and OEX
(2) the Philly would let you trade DELL
(3) the AMEX would let you trade INTC and MO
(4) the P-Coast would let you trade MSFT
Obviously, there were more issues at each exchange, but I am using this as an example.
So, assume that you needed to purchase a membership at each exchange. These numbers are all fictional.
(1) CBOE = $700,000 for a seat
(2) AMEX = $600,000 for a seat
(3) Philly = $200,000 for a seat
(4) P-Coast = $300,000 for a seat
Then you add 2 clerks for each exchange at $30,000 per year. Add telephone, quotes, etc. and this adds up to a bunch of money.
Today, although options are multiply listed, there is still no linkage program for every option at every exchange. Thus, there are still a lot of trade throughs and too much fragmentation. This is unlike the stock side where the Chicago ITS or Philly ITS can hit a NYSE bid or take out an offer instantaneously.
Thus, as you can see, it is very expensive to do business in the options market and it still is. The ISE does help because it eliminates clerks on the floor, but until there is a genuine market linkage similiar to the ITS on the equity side, it is going to be difficult to get costs down.