Prices are fixed by law. Unless a plan is marked up by a service provider or broker (this is unusual), the price of an insurance plan is the price of the plan regardless of the source.  Identical plans will have identical rates down to the penny.

Now what can drastically fluctuate is the cost of the Health Savings Account that accompanies your HDHP (why should I have an HSA with my HDHP?)

The major components of a Health Savings Account that have varying prices from bank to bank are:

• Account Setup Fees
• Account Maintenance Fees (monthly or annually)
• Account Balance Fees (if it’s below a certain amount for example)

What also needs to be taken into consideration when picking a bank for your HSA is the interest rate.  While this should not be the only determining factor when picking a bank, interest rates can fluctuate quite a bit from bank to bank, especially if you are planning on carrying a large balance.  For example many banks pay a higher interest rate if you carry a balance over a certain threshold, $5000 for example.