When a product is super complex, fixed pricing might not make sense. I wouldn't ask a general contractor "how much would it cost to remodel my kitchen?" before they have seen my home (especially because I don't because a kitchen!)
You shouldn't be forced to "call for pricing".
If you want to walk in with the attitude that you know what is best, I recommend writing down what you need and why you need it in advance, so you can communicate you know what your needs are without insisting on a solution. The recommended thing may or may not be what you thought you wanted. If you can't write down your needs clearly and concisely, buying what you thought you wanted is likely to turn into an expensive waste of time for all parties.
Source: was good salesperson in a former life