Basic road bike for races

Bike shops might have some used inventory.  

I have bought 2 bikes off E-Bay.  Both have worked out OK for me, but in both cases, I was prepared to "throw away" the bike if it wasn't safe to ride.  

Size is important.  Online fit calculators get you close, but actual fit is as much personal preference as anything.  

While I haven't browsed recently, the used bike market tends to be:
1)  Mid-range or higher bikes selling at a 50% discount (So a $4000 bike offered for $2000).
2)  Antique bikes selling cheap  ('80's or '90's bikes for <$100)
3)  Low-end bikes with an asking price 20% less than new (A 2 year old Trek for $600).  

If the steel-frame bike fits, ride it!  I did my HIM on a mid-80's Raleigh Technium and averaged 20+ mph.  

Dallas and Austin have strong markets for Triathlon equipment.  When I was living in Texas I always found lots of good options on Craig's list from people who go into the sport then dropped out after less than three years.  They had very nice equipment that was 1/3 the price of new equipment of similar quality/condition.  I haven't had as good of luck on in smaller Triathlon markets on Craig's list but if you keep checking back something should pop up.  My brother had good luck with ebay when he was training for Ironman back in 2002. I am not as good of an ebayer as he is though.