CPA's, like attorney's, have a wide variance in how they conduct their practice. Some charge a retainer fee as you are indicating here (regular periodic payments, etc), all based on a level of service.
so for example: if a CPA is maintaining your books, then they will want to be paid a FMV for thier services. Like wise,when they prepare your taxes the want to be paid for that. It is only fair.
so the question is, how much do you expect a CPA to work for? 8 dollars an hour, 35 dollars an hour, maybe, 150 dollars an hour?
so if the person is maintaining your books, where you turn in copies or receipts and invoices, then 150 dollars every quarter is very reasonable. It takes 2 or 3 hours and sometimes more to put together receitps and invoices and to categorize the expenses to the balance sheet and chart of accounts.
like wize if that person is doing quarterly taxes, it could take as long as 8 to 12 hours to do the taxes, again making the price you are quoting very reasonable.
So roughly, I believe the price you are being quoted is very reasonable. Expensive would be 1250 dollars or more per year. IN the Fremont area the average hourly rate for CPA business services is between 74 and 125 dollars an hour.
In tyring to lower the rate talk to the referred CPA about what you can do to get a discount on his rate. Perhaps you are already doing it. Ask him for example: What if I use software like quickern or peach tree, and bring him the data files instead of paper.
If your book keeping software is compatible with his software, it will save him time and effort.
I do not know the level of service you are retaining, but ask him if you categorize the receipts ahead of time would that reduce the cost.
You can also negotiate by signing a long term retainer and asking him to charge based on a sliding scale commensurate with your gross or net revenues.