I ordered paint from Tieman as well. I think a quart was ~$110 delivered. Your best option might be to order a quart and have it put into aerosol cans locally. I also had a quart mixed locally using the paint formula for 71-73 from the Pontiacpower website and the match was not good. Here's a sample comparing the Pontiacpower to the Tieman formula.
Tieman paint is the lighter two swatches
If you just want to buy cans, you might try the OER paint from Classic Industries. When I redid some honeycomb rims, I would not pay the OEM prices and bought the honeycomb paint from OER. It was a high quality product. They have a listing for 71-73 Pontiac Blue at $16.99, but I cannot vouch for the color match.
http://www.classicindustries.com/fir...ts/k89210.html