Price comparison (estimated cost incl ground shipping to my address and core charge):

Sam Taylor Buick: $505.00
GMPartsDirect.com: $565.18
NewGMParts.com: $602.91
SummitRacing.com: $492.90
GMPartsGiant.com: $616.99
AdvanceAutoParts.com: $662.39 ($535.91 with 20% discount code that expires today)

As 1993Z noted in the post below Amazon seems to be a good source to get it for around or under $400.
A Google search of the part number (10457702) can sometimes find a good deal.

Thanks to everyone for your help!

Troy

 

I just ordered one for my 93 from Amazon for $360.81. It showed it was the last one in stock. Here is one from AC direct for $373.02 http://ac-direct.amazonwebstore.com/...B000EQL0PO.htm

 

I was going to get it from ac-direct, but the site had a banner that said: "Sorry for any Inconvience Site Being updated Will return Bigger and Better Very soon !!". I emailed them to make sure they were open for business and the email bounced. This kind of stuff makes me very uneasy... so I checked Amazon only to find they had more in stock. My Amazon.com shipment is due to arrive tomorrow.

Thanks for the Amazon tip 1993Z... saved us some cash!

 

We put the new opti in and got it back together yesterday and it is running great! Thank you all again for your help.