I recently purchased and installed this item. It is a plug and play for your Gen 1 oem radio. I paid $29.95 + $9.95 shipping for a total of $39.90.
EBay iPod MP3 accessory
If the link doesn't work it may have expired so try searching for "HONDA CIVIC ACCORD CRV OBYSSEY iPOD iPHONE MODULE" on eBay. The shipping was slow (2.5 weeks) even though the item only had to travel 200 miles.
I researched many other vendors and there were a few that offered a similar product for quite a bit more money. This is an example:
Grom Audio Adapter
If you need an 3.5mm audio cable they can be purchased for $1.50 - $1.60 ($4.33 shipped) at
Monoprice
I put in a s2000 radio with cd player (that I picked up for $20 off the
s2k.com website) earlier which was a direct plug in as well. The connector also worked in my oem Insight radio. This will work if you
do not have the cd changer hooked up in your vehicle and the smaller slot on your radio is open. I like it because I have both an iPod and MP3 player and both of them can be connected and accessed by pressing the CD button on the radio. The sound is good (I had added the Polk DB 651's in the back and DB651S's in the front after my first long road trip).
The MP3 3.5mm audio cable was not included in my purchase but I had an extra one. I fished both cables to the change box so they are hidden and easily accessible. The iPod is suppose to charge through the provider connector although I can't confirm for sure that it does because I only drive about twice a week.