Best option for AUX input

I have a Clarion M5475 marine CD player in my boat right now. I just have a simple system with 4 Polk DB651s run off of the receiver's built in amp and 4 more DB651s on the tower powered by a 200 watt (Max) HiFonics Zeus amp.

I'm perfectly happy with this setup accept for the fact that I have good data service where we run the boat on my iPhone 4 and could be using Pandora instead of staticy radio stations with long commercials.

My research tells me that many have tried and failed to reverse engineer the CD changer input on this receiver and make a cable to create an AUX input. Many have been successful with the Clarion XMD-1 but not the M5475.

Anyway, I've already blown my accessory budget out of the water this year with a PerfectPass Stargazer and I still want more ballast so this has to be done on a budget. I figure I have 2 options:

1) The most obvious- Replace the receiver with another one for $150-200. I'd try to sell the Clarion for what I can get for it on Craig's List to offset some of the cost. I'd like a super slick one with iPhone controls but I have my doubts about that working well with Pandora rather than the built in iPod app. Does anyone have any experience with one of these and Pandora or Slacker? Can you skip and what not through the receiver's controls?

2) Buy a cheap EQ with aux input- I see some of these that are in the $50 range.

Any recommendations given the above scenario? Also, I'm hesitant to spend much on a non marine receiver given the fact that there are marine options on the low end of that price range.