Wetsuit, no wetsuit, or maybe just rent...

My first triathlon is two weeks from today, Tri America in Louisville Ky, IN the Ohio River. I have only done one open water swim with no problems, but then again it was not in the MUDDY, FLOWING waters of a HUGE RIVER!!

Anyways, I came across a thread on the Tri American board asking if a wetsuit was needed/preferred at this particular swim, and someone answered with a resounding YES!!

As luck would have it, I don't own a wetsuit.

So naturally I freaked, and called my tri expert (but pregnant) sister (otherwise known as my "made coach" - but I digress) She told me that last year, about 80% of the people had wetsuits on, mainly because of the river seemed a bit choppy and cool that day, and for the added buoyancy(confidence)

The water temp today according to the corp of engineers is between 74-76 degrees, and more often then not the river is as smooth as glass, and the water is down.

So should I rush and buy a entry level longjohn wetsuit - any opinions on ProMotion wetsuits?
Or buy a closeout QR, quickjohn (wetsuit shorts) that is still $20 more then the ProMotion longjohn, or does anybody have any experience with...

RENTING YOUR WETSUIT FROM TRIBONZIA!!!

I like having nice things, and I just hate the notion of tossing out $150 minimum on something that I won't like next year, I always thought I would just chew over my decision on what wetsuit to get this winter. I am checking ebay, but have time restraints.

Suggestions, advice?